[clang] [HLSL] Add testing for space parameter on global constants (PR #106782)

[Damyan Pepper via cfe-commits]

https://github.com/damyanp approved this pull request.

I'm marking this as approved - I think that there's some cleanup and rearranging of the tests here that would improve this change.

It might be worth trying to get a review with someone who has more experience of testing strategies for these sorts of diagnostics than I do.

https://github.com/llvm/llvm-project/pull/106782