audiosink: expose more audioringbuffer vmethods to child sinks
Submitted by Philippe Renon
Link to original bug (#788361)
The existing reset vmethod is deprecated.
The audio sink will fallback to calling reset if pause or stop are not provided and will fallback to calling start if resume is not provided.
Existing audio sinks continue to work as before.
This change is needed for sinks that need to distinguish between a pause and a stop (currently both are handled by a reset).