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

[Andy Kaylor via cfe-commits]

andykaylor wrote:

It would be useful to pull the CIR dialect changes out of this and into a separate PR that precedes this one. You could also Move the CFG flattening into a follow-up PR and just not lower to LLVM IR in this one. Those changes would make this easier to review.

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