u_threaded,freedreno: threaded_context support

The first three patches are from !9321 (merged) and !9316 (merged) which are needed to prevent regressions. Other than that I'm marking this as 'Draft' because some cleanup still needed on the freedreno parts of this. Async-flush and async pipe_debug still need a bit of wiring up. But I think the threaded_context patches are ready for review. (+ @mareko for threaded_context patches)

One remaining CI a630-traces fail, still need to check if that is legit or not