[clang] [clang][Sema] Diagnose exceptions only in non-dependent context in discarded `try/catch/throw` blocks (PR #139859)

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Sirraide wrote:

> In addition, I think there is value to considering an additional flag that works with `-fno-exceptions`/etc to allow in `consteval` functions, which I think gets us most of the `constexpr` uses that folks will care about, and be implimentable trivially after this patch is merged.

Yeah, I agree there should be some way to enable exceptions only during constant evaluation once we support that.

https://github.com/llvm/llvm-project/pull/139859