Onboard to central package management in NuGet.Client repo

[jeffkl]

Bug

Fixes: https://github.com/NuGet/Client.Engineering/issues/1969

Regression? Last working version:

Description

• I tried using git mv on packages.targets but I changed too much of the contents so it looks like a delete/add 😢
• Organized all of the package versions in Directory.Packages.props
• Added GlobalPackageReference items for PackageReference items that were in common imports
• Used <PackageReference /> instead of <PackageDownload /> since CPM doesn't support PackageDownload. This brought in new dependencies which weren't being pulled in before so I had to resolve all of the conflicts with a few new package versions and/or PrivateAssets/ExcludeAssets.
• Removed logic that verified package versions were declared in one place since CPM does that
• Used GeneratePathProperty in a few places
• Had to include some interfaces for project.json in Test.Utility since I think they were removed from newer versions of Microsoft.VisualStudio.ProjectSystem.Managed. They are just using ComImport so it should be okay.
• Writing an empty Directory.Packages.props to the .test folder

PR Checklist

• PR has a meaningful title

• PR has a linked issue.

• Described changes

• Tests

  • Automated tests added
  • OR
  • Test exception
  • OR
  • N/A

• Documentation

  • Documentation PR or issue filled
  • OR
  • N/A

[zivkan]

I don't like the "enumerate every dependency of package X and add a <PackageReference Inlcude="x" ExcludeAssets="all" /> as an alternative to <PackageDownload. But everything else is opinionated, so if others approve I won't complain if it gets merged as is.

[nkolev92]

We probably need to wait to merge this until we know 100% all the CIs have 17.4.

We should also update our requirements section for building the repo.

I forgot about the comment about changing the repo readme.md or contribution.md to mention minimum VS version numbers required to build the repo

[jeffkl]

I forgot about the comment about changing the repo readme.md or contribution.md to mention minimum VS version numbers required to build the repo

Good idea, I have updated the CONTRIBUTING.md to indicate you need VS 17.4+ and .NET SDK 7.0+