[llvm] [lit] Support GoogleTest test discovery through prefixes, too (PR #137423)

[Reid Kleckner via llvm-commits]

https://github.com/rnk commented:

Looks good, but I don't see any new test above Inputs that uses the new test inputs. Was that a missing file you needed to `git add`?

https://github.com/llvm/llvm-project/pull/137423