Support rank 1 multidim arrays.

Not saying this is a must-do - just need an issue comment for a disabled test.

[MichalStrehovsky]

@atsushikan this works fine with the open source CoreRT compiler.

It's a bit odd to track the closed source, UWP-only compiler limitations in the public repo. We might want to come up with a label for this kind of issues if tracking on GitHub is a must, but I would prefer not to track issues like this here. It's not actionable from this repo.

[MichalStrehovsky]

Turns out there's interesting behaviors we still don't cover in the runtime/compiler even on the CoreRT side.

Once we cover those, we're free to bring down the limitation on the ProjectN side (in terms of reflection/type loader). Statically, we'll still not support them with the ProjectN compiler, but that will fix itself with time. The test blocked on this on the CoreFX side doesn't test the static case as that's only available in IL.

See dotnet/coreclr#11034.

Reopening and assigning to myself - need to now reenable those corefx tests that we disabled with this issue.

Tests reenabled.