Add Helix project and supporting targets

[jander-msft]

Summary

These changes enable the use of Helix for executing tests on a multitude of platforms and architectures. Helix testing is enabled through the use of the /eng/helix/Helix.proj project and can be executed on the command line using build.cmd/sh -projects ./eng/helix/Helix.proj -test -skipnative -skipmanaged after a successful full build of both native and managed components.

Details

• The /eng/helix/Helix.proj project gathers the executable work item information (e.g. dotnet test command line) from each participating project (e.g. test projects).
• These work items (e.g. tests) are executed in a set of queues. There are several queues that are employed to get broad coverage of scenarios where .NET Monitor is used; the set of queues on which the work items are executed are determined by the build target environment e.g. a Windows x64 host can launch arm64, x64, and x86 tests on Windows queues depending on which target architecture was built.
• Test results are automatically uploaded to Azure Pipelines if this project is invoked within an Azure Pipelines build (no work was done here since this is automatically supported by the Helix SDK).
• All existing enabled tests are runnable and succeed through this project EXCEPT for the Azure blob storage tests that require Azurite to be installed; these tests are automatically skipped since Azurite is not initialized and the environment variable to indicate they should not be skipped is not applied. Enabling this is still a work in progress.
• The pipelines have not been update to use this project yet; that will come as a separate PR.

Example build where E2E testing via Helix is enabled: https://dev.azure.com/dnceng/internal/_build/results?buildId=2218286&view=results

Release Notes Entry