[clang] Add flag to opt out of wasm-opt (PR #95208)

[Quentin Michaud via cfe-commits]

mh4ck-Thales wrote:

@sbc100 I tried to limit the scope of this new option to Wasm using the corresponding group in `Options.td` (https://github.com/ThalesGroup/llvm-project/blob/8c7052d5da074eb1d754aeddc4257d33e4e299aa/clang/include/clang/Driver/Options.td#L222), but for some reason I was unable to make it work.

@sunfishcode Is there a kind of deprecation process in LLVM, when we can warn of breaking changes ? Otherwise not sure how to handle it. 

https://github.com/llvm/llvm-project/pull/95208