Gen facades cleanup

[ViktorHofer]

• Remove the ILRewriter path in GenFacades
• Avoid custom GetCompileItems target in favor of the exposed SourceFilesProjectOutputGroup target so that the GenFacades package doesn't need to be referenced by contract projects anymore.
• Perf improvements by a) not reading the exclusion file inside a loop for every passed in source file when generating a PNSE and b) not dumping the original assemblies by default for zero version seed rewriting.
• Minor code cleanup in GenAPI.targets, i.e. not exposing the IntermediateTargetPath property in it
• Some more style nits to avoid accidental target or property name binclashes by underscoring _ internal ones.

Before merging I want to wait for dotnet/runtime#52793 to be merged and then test the change in dotnet/runtime via a private package feed.

[ericstj]

One thing I was thinking about as interesting to potentially improve perf would be moving this to a C# source generator.

[ViktorHofer]

One thing I was thinking about as interesting to potentially improve perf would be moving this to a C# source generator.

The not supported compile file is definitely a valid use case for a source generator. Would be interesting how much work it would be to switch from the task to the source generator and how much time we would save by that.

[ericstj]

LGTM, make sure we thoroughly test the cleanup.

[ericstj]

Surprised me to see this, I realized it was because Cci.Extensions didn't use the property:

arcade/src/Microsoft.Cci.Extensions/Microsoft.Cci.Extensions.csproj

Line 21 in 14c87f6

<PackageReference Include="Microsoft.Cci" Version="4.0.0-rc3-24214-00" />

[ViktorHofer]

Tested locally against runtime main and found some issues which I fixed in the last commit. Merging.