[cDAC] Run runtime-diagnostics pipeline on more platforms

[max-charlamb]

Currently the runtime-diagnostics pipeline runs its test on the ADO machines, not Helix. We would like to move to helix to support other OS/Arch combinations.

Given the runtime-diagnostics pipeline is a wrapper around the diagnostics PR pipeline (with a live runtime) we have agreed the easiest path forwards is to modify the diagnostics pipeline to use Helix and invoke it from the runtime repo.

Steps to run the diagnostics pipeline on helix:

• Decouple building tests from running tests to allow packaging the tests for Helix - Move tests and test debuggees to repo root 'tests' directory diagnostics#5554
• Support running diagnostics tests out of proc. Several of the diagnostics tests require 'debuggees' which make the tests platform dependent more so than normal managed tests.
  • DbgShim Tests - Move tests and test debuggees to repo root 'tests' directory diagnostics#5554
  • SOS Tests
    • SOS UnitTests build some debuggees at test-time. This may cause problems on helix.
• Package tests for helix
  • Modify single file to prevent compile at test time, compile - We don't want to compile any code on helix. Several 'unit' tests compile single file debuggee apps. These should be able to be compiled ahead of time.
  • Use relative paths instead of absolute paths to allow for running locally and on helix
• Modify pipelines to push tests to helix
  • Move non-debugger test to helix

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