Perform symbol publication using Microsoft.SymbolUploader.Build.Task (#10358)

- aspnet/AspNetCore-Internal#2126
- allow release pipeline to publish symbols on all builds: #10113
- add new project that publishes symbols to MSDL and SymWeb
  - release pipeline prepares then restores and builds the new project
  - expire symbols after 10 years (or so)

nits:
- add `$env:DOTNET_SKIP_FIRST_TIME_EXPERIENCE` to ci.yml