MATLAB Cache fixes

[davidbuzinski]

This PR addresses 2 issues:

• Warn instead of hard error if GitHub Actions cache is unavailable: setup-matlab@v2 with cache: true: Post setup fails randomly (not very often)  #98
• Fix unclear errors for macOS and Windows if user uses actions/cache action: Conflict between actions/cache and setup-matlab@v2 #93

[davidbuzinski]

I made a few more changes:

• In our Windows workaround I added the restore for tool cache into a try-finally block because if steps were failing we were leaving the tool cache as the wrong directory
• If windows is not detected in the cache as completed due to missing .complete file or some other reason, we were getting problems with the symlinks against a partially completed install
• add awaits for io.rmRF because I was seeing some weird control flow errors

[mcafaro]

Why is this env variable changed above? I don't see it being used after it is change.

[mcafaro]

Oh, I guess it's used by tc.cacheFile behind the scenes?

[davidbuzinski]

It is used inside GitHub's tc.cacheFile code (and some of the other tool-cache functions) to locate the tool cache directory on the runner. We set it to the same location on D: to create/ link the install directory then we restore it to it's default C: location at the end.

[davidbuzinski]

Oh, I guess it's used by tc.cacheFile behind the scenes?

Yeah exactly