gh-159136: Avoid stop-the-world when setting function name attributes (gh-159269)

Setting __name__, __qualname__, __doc__ or __module__ on a function
stopped the world in the free-threaded build since gh-154826 and
gh-154851, making functools.wraps() orders of magnitude slower with
multiple threads.

Use the per-object critical section and _PyObject_XSetRefDelayed()
instead, as gen_set_name() already does.  Use acquire loads in the
readers and hold strong references across error reporting, tracing, and
eval-frame recording that may execute Python or detach the thread.  The
__code__, __defaults__, __kwdefaults__ and __closure__ setters still
stop the world to clear func_version.

Document synchronization requirements for direct field access and the
lifetime of borrowed function attributes.