[compiler-rt] [Coverage] Add testing to validate code coverage for exceptions (PR #133463)

[Justin Cady via llvm-commits]

justincady wrote:

Ping. :)

Updated the description to make it clear this is a test-only change. It just validates existing coverage behavior in anticipation of other changes.

cc @chapuni @MaskRay @ZequanWu @evodius96 

https://github.com/llvm/llvm-project/pull/133463