Add error check for skipped tests in merged groups

[markples]

If I test is written in the old style (with a Main and OutputType==Exe without an attribute such as RequiresProcessIsolation) in a merged test group directory, it will be skipped. This change adds a check to detect those cases.

I have struggled with ways to automatically set OutputType. Directory.Build.props is too early (the test project file will override it). Directory.Build.targets is too late as the C# targets files will already have been processed and set other variables based on the value of OutputType. This Target doesn't execute until later, but since it is an error it doesn't matter how those additional properties were set.

Since this adds more boilerplate to each merged test directory, I created a src/tests/Directory.Merged.props to share all of that.

This catches 3 tests that aren't currently executing.

Unrelated:

• Use GetPathOfFileAbove in nearby locations for Directory.Build.props chaining rather than specific paths
• Fix two easy IL warnings that appeared in my local build of all tests

Resolves #84182

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Issue Details

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If I test is written in the old style (with a Main and OutputType==Exe without an attribute such as RequiresProcessIsolation) in a merged test group directory, it will be skipped. This change adds a check to detect those cases.

I have struggled with ways to automatically set OutputType. Directory.Build.props is too early (the test project file will override it). Directory.Build.targets is too late as the C# targets files will already have been processed and set other variables based on the value of OutputType. This Target doesn't execute until later, but since it is an error it doesn't matter how those additional properties were set.

Since this adds more boilerplate to each merged test directory, I created a src/tests/Directory.Merged.props to share all of that.

This catches 3 tests that aren't currently executing.

Unrelated:

• Use GetPathOfFileAbove in nearby locations for Directory.Build.props chaining rather than specific paths
• Fix two easy IL warnings that appeared in my local build of all tests

Completes #84182

Author:	markples
Assignees:	markples
Labels:	test-enhancement, area-Infrastructure-coreclr
Milestone:	8.0.0

[markples]

PTAL @trylek @jkoritzinsky
cc @dotnet/jit-contrib - I think the process of going through this (D.B.props/targets, etc.) may help with fixing BuildAsStandalone

[markples]

/azp run runtime-coreclr outerloop

[azure-pipelines]

Azure Pipelines successfully started running 1 pipeline(s).

[trylek]

Looks great to me, thanks Mark for cleaning this up and for fixing the previously overlooked cases!

[BruceForstall]

IMO, it would be helpful to have some comments. Especially, to describe why we need this weird _il_d/_il_r handling.

[trylek]

Both errors you are seeing in the outerloop run should be fixed now by my and Michal's PR

#84268

I merged it in earlier today but after you triggered the outerloop runs.

[markples]

Thank you all. @BruceForstall I will fold that into my next changes (to merge immediately since a new check and new tests are a race condition in the repo)