Generic ID management code can now do those local temp copy handling, so
no need for duplicated own code for that.
No behavioral changes expected here.
When sequencer was moved from kernel, the DEFINES based on audaspace
were not moved along.
That means users had no way of creating new audio strips since
BKE_sequencer_add_sound_strip was ifdef'out
This is first step of refactoring task T77580.
Next step will be breaking up files into smaller ones.
Reviewed By: sergey, brecht
Differential Revision: https://developer.blender.org/D8492