[clang] [NFCI][sanitizer] Refactor parseSanitizeTrapArgs (PR #119797)

[Thurston Dang via cfe-commits]

thurstond wrote:

> Would be possible to switch DiagnosedAlwaysRecoverableKinds to this function?

That's a bit more complicated because it has Unrecoverable and AlwaysRecoverable error cases (vs. the current function only has one error case: ~Supported). I'll refactor RecoverableKinds in a follow-up patch.

https://github.com/llvm/llvm-project/pull/119797