Protected packages: Show protected label in packages list

MR includes:
- Feature flag switch to enable / disable the protected label
- Add badge to package in package list
- Extend graphql api to include package protection rules
  in graphql type Types::Packages::PackageBaseType
- Add association in model Packages::Package
  for matching package protection rules
- This commit is only a proof of concept
  in order to see if this is going in the right direction

Changelog: added