Addresses issues where background Java processes causes builds to hang.
Added diagnostics to capture running processes on CI builds.

* Update build.cmd to install .NET Core into $repoRoot/.dotnet instead of $repoRoot/.dotnet/x64
* Move restore sources from build/sources.props into eng/Versions.props (following arcade conventions)
* Remove usages of RuntimeFrameworkVersion in tests and build
* Update Blazor VSIX to use Arcade VSIX tools
* Rename Common.Tests to IIS.Common.TestLib and make it a test asset
* Remove custom versions props for ANCM installer code
* Remove duplicate references to xunit and remove usages of IsTestProject
* Remove duplicate references to Internal.AspNetCore.Analyzers
* Import Arcade.Sdk props and targets and remove custom versioning props
* Remove references to Internal.AspNetCore.Sdk
* Rename PackageLicenseType => PackageLicenseExpression
* Remove dependency on tasks in Internal.AspNetCore.Sdk, add ref to Internal.AspNetCore.BuildTasks as a temporary workaround
* Use Arcade's nuspec support
* Rename SignalR.Client.FunctionalTests to SignalR.Client.FunctionalTestApp
* Fixes for changes to property evaluation order
* Update BaseLineGenerator to netcoreapp3.0
* React to changes in evaluation order in RPM files and quirks in using <Exec> instead of <Run>
* Update Microsoft.Extensions.ApiDescription.Server to react to changes in Arcade packaging
* Workaround aspnet/AspNetCore#11009

Add new build.cmd/sh options for suppressing restore, NodeJS, setting target arch and OS name, and more (#7137)

Add new command line parameters for working with the project:

* `-NoBuild`, `-NoRestore` - these already existed, but users found it hard to discover this powershell syntax: '-build:$false'
* `-Arch`/`--arch` - set the target CPU architecture to build. Defaults to x64
* `--os-name` - on non-Windows builds, manually specify if the build should target Alpine. generic Linux, or MacOS
* Rename flags used to build specific project types. The pattern now is `--build-$(group)` or `--no-build-$(group)` (In PowerShell its `-Build$(Group)` or `-NoBuild$(Group). Example: -NoBuildJava

Changes to build definitions:
* Update the ci build definition to build all supported architectures
* Support publishing multiple artifacts per job

Other changes:
* `-NoBuild` implies `-NoRestore`
* Add new properties, `TargetArchitecture`, `TargetOsName`, and `TargetRuntimeIdentifier`
* Replace usages of `SharedFxRid` with these new properties
* To make `--no-build-nodejs` actually work, replaced Components.Browser.JS.csproj with Components.Browser.JS.npmproj
* Fix errors when building for win-arm on a clean machine
* Fix a few other project errors, like using the wrong syntax for DefaultItemExcludes, or using the wrong Platform value for x86

Update the build scripts to support building subfolders or subgroups of projects

* Add build scripts for ci
* Remove obsolete scripts
* Add flags like --test and --pack to control running just test or packaging
* Add flags like --managed and --native to control building sub-types of projects
* Remove KoreBuild bootstrapper flags
* Update to extensions 3.0.0-preview.18619.1 (needed to get a fix for aspnet/Extensions#815 to make this change work on MSBuild.exe)

Prior to reorganization, this source code was found in https://github.com/aspnet/Identity/tree/4a717c85635671e04c8691fe3c125a77ee46d32a

Prior to reorganization, this source code was found in https://github.com/aspnet/Identity/tree/4b3d8e5106158fb29da33c8e14134ed168a5e880

Prior to reorganization, this source code was found in https://github.com/aspnet/Identity/tree/fa3cfd08eb6af819adc5fef2d9b603638c4b4b3b

Prior to reorganization, this source code was found in https://github.com/aspnet/Localization/tree/0bcac31dd705fb9db60723f5d7eaeffb728358f5

Prior to reorganization, this source code was found in https://github.com/aspnet/BasicMiddleware/tree/1de636cd18309070792b68888ca29c8b85fac98b

Prior to reorganization, this source code was found in https://github.com/aspnet/Razor/tree/582f3f867eeb8fca00e6b328faf7665c9a98476c

Prior to reorganization, this source code was found in https://github.com/aspnet/MvcPrecompilation/tree/3cd4de8af8322b90e62a5818ece90428e2dc933b

Prior to reorganization, this source code was found in https://github.com/aspnet/Mvc/tree/c9887e027a97b07a3ae7699112b9a2620a36e553

Prior to reorganization, this source code was found in https://github.com/aspnet/SignalR/tree/c852bdcc332ffb998ec6a5b226e35d5e74d24009

Prior to reorganization, this source code was found in https://github.com/aspnet/Razor/tree/8ba0a894256e4b5c5385db9b5aac32fdbd046f3a

Prior to reorganization, this source code was found in https://github.com/aspnet/MvcPrecompilation/tree/032768b063a768559c8dfaea0d06380da77307ae

Prior to reorganization, this source code was found in https://github.com/aspnet/Mvc/tree/a6199bbfbab05583f987bae322fb04566841aaea

Prior to reorganization, this source code was found in https://github.com/aspnet/SignalR/tree/d0bcdf3dd92afba858fca2871535faf4594c81de

Prior to reorganization, this source code was found in https://github.com/aspnet/Razor/tree/fd4572874e41ca3af803b0b2c71955505dd4bde5

Prior to reorganization, this source code was found in https://github.com/aspnet/MvcPrecompilation/tree/617586a984b1eff9ca0ca8126dd0b1dab2ea16f2

Prior to reorganization, this source code was found in https://github.com/aspnet/Mvc/tree/5a4fd3e792e75619e3b1de069fabdf87d2cd0983

Prior to reorganization, this source code was found in https://github.com/aspnet/SignalR/tree/bc148a07244a451e48b7e0efdf16db8f69f788ff

Prior to reorganization, this source code was found in https://github.com/aspnet/Security/tree/26d27d871b7992022c082dc207e3d126e1d9d278

Prior to reorganization, this source code was found in https://github.com/aspnet/Routing/tree/c28c7dea4e866ec5a0d33f0e290bc49baadb1c85

Prior to reorganization, this source code was found in https://github.com/aspnet/ResponseCaching/tree/12395b4d1c03e49134704679f94af6f328a7e1d5

Prior to reorganization, this source code was found in https://github.com/aspnet/HttpSysServer/tree/d4f588658218ef59c8ae14261e323efa6d8a8156

Prior to reorganization, this source code was found in https://github.com/aspnet/CORS/tree/c39d85f6df58ecb4507fd3d2a2d9f8d36054922b

Prior to reorganization, this source code was found in https://github.com/aspnet/Antiforgery/tree/8124442320b6de41a89bd779dd1b82b5bb8131e7

Prior to reorganization, this source code was found in https://github.com/aspnet/Security/tree/93926543f8469614c2feb23de8a8c0561b8b2463

Prior to reorganization, this source code was found in https://github.com/aspnet/Routing/tree/3d828221a19d91907c52c2f40928b019bee1ef92

Prior to reorganization, this source code was found in https://github.com/aspnet/ResponseCaching/tree/9f49398f28d7c1e0dc0305f8080351c413b0f297

Prior to reorganization, this source code was found in https://github.com/aspnet/HttpSysServer/tree/3e08bf8833827737a5bd1b64210c7a5e8e2941ec

Prior to reorganization, this source code was found in https://github.com/aspnet/CORS/tree/f05b0e792d2361be214947798857ef3eac77825d

Prior to reorganization, this source code was found in https://github.com/aspnet/Antiforgery/tree/9e5146cff912ebbd003d597eb055144e740759fa

Prior to reorganization, this source code was found in https://github.com/aspnet/Security/tree/930ed239e41d7547edf06f31efa3461d1a2c6bad

Prior to reorganization, this source code was found in https://github.com/aspnet/Routing/tree/58b66f7cbb3858aa1b7b8b2848b8d3cec4df0e40

Prior to reorganization, this source code was found in https://github.com/aspnet/ResponseCaching/tree/777b2fbf7e768221c528243773037a50423b7b34

Prior to reorganization, this source code was found in https://github.com/aspnet/HttpSysServer/tree/d8d1f36f28359b76f838a99e425b2af2565538f0

Prior to reorganization, this source code was found in https://github.com/aspnet/CORS/tree/ec429447bfd5f419b9f40676b03b85a954b40f74