Building linker tests spawns hundreds of NuGet out-of-process restore executables

[ViktorHofer]

When building linker tests, NuGet is invoked per generated linker test project which a) performs poorly and b) is a can for NuGet instability issues. We should usually only invoke NuGet once for all projects as we do for all other projects in dotnet/runtime (besides for tasks).

This is achievable via a wrapper project that defines dependencies via P2Ps to all the generated linker projects. That wrapper project file already exists today (tests.proj). Generating the linker projects would need to happen before tests.proj is restored so that the dependencies are defined "statically".

cc @joperezr @eerhardt

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Issue Details

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When building linker tests, NuGet is invoked per generated linker test project which a) performs poorly and b) is a can for NuGet instability issues. We should usually only invoke NuGet once for all projects as we do for all other projects in dotnet/runtime (besides for tasks).

This is achievable via a wrapper project that defines dependencies via P2Ps to all the generated linker projects. That wrapper project file already exists today (tests.proj). Generating the linker projects would need to happen before tests.proj is restored so that the dependencies can be defined in-time.

cc @joperezr @eerhardt

Author:	ViktorHofer
Assignees:	-
Labels:	area-Infrastructure-libraries
Milestone:	-