[clangtidy] Allow safe suspensions in coroutine-hostile-raii check (#72954)

Certain `awaitable` types could be safe to `co_await` on even when we
have suspension-hostile RAII objects in scope.
This PR adds a way for users to mark such safe `awaitable` and silence
false positive warnings in `co_await` expressions involving such an
`awaitable`.

`co_await`-ing an expression of `awaitable` type is considered safe if
the type is part of `SafeAwaiatablesList` check option. RAII objects
persisting across such a `co_await` expression are
considered safe and hence are not flagged.