[clang] [llvm] [WebAssembly] Implement an alternative translation for -wasm-enable-sjlj (PR #84137)

[Sam Clegg via cfe-commits]

sbc100 wrote:

> @aheejin @sbc100 let me confirm the plan on this PR. i can remove the option `-mllvm -experimental-wasm-enable-alt-sjlj` by making it unconditionally true, and update tests, right?

That is my understanding yes.

https://github.com/llvm/llvm-project/pull/84137