Address analyzer and generator torn state with Visual Studio

[marcpopMSFT]

Per #41790, this issue is to track the work that is required.

• Using SDK compiler in torn builds #41791
  • Use PackageDownload in torn builds #41951
  • Fix detection of torn SDK #41907
• Analyzers that can should separately insert into Visual Studio
  • ✅Razor
  • Roslyn
  • Roslyn-analyzers
• Analyzers that can't easily, should insert with the SDK
  • runtime, aspnet, windowsdesktop
  • Identify where those analyzers come from
  • Created a transport package similar to our existing ones (VS.Redist.Common.Net.Core.SDK)
  • Create VS setup authoring either included in the transport package or listed on the VS side
  • Change the compiler to load the analyzers from the VS location when expected
  • Create a package version in the .NET version props file
  • Enable ngen in VS

[marcpopMSFT]

Per our meeting, I created a new issue to outline the work and linked to your design PR and your issue tracking the work for the msbuild.exe case. Feel free to update, @jaredpar