[clang] [CIR] Upstream Exception CXXTryStmt (PR #162528)

[Amr Hesham via cfe-commits]

AmrDeveloper wrote:

This PR now contains basic support for try block with non-call ops and empty catch all.

Some notes :D
- Moving allocas to the parent scope of try op will be in a follow-up PR.
- I will experiment with converting the try scope into a normal one BB, if there are no handlers.
- I will also experiment with removing or not generating BB with no predecessors

@andykaylor @bcardosolopes 

https://github.com/llvm/llvm-project/pull/162528