[AudioToolbox] Improve AudioFile API a little bit. (#23745)

* Add numerous overloads that returns the error code, obsolete other overloads.
* Some code updates as well.
* Update a lot of the xml docs.
* Update tests to:
  * Verify the status code.
  * Use the temporary directory instead of the Documents directory.
  * Clean up after themselves.

Author: rolfbjarne