bluez5: add LC3plus A2DP vendor codec
Add another A2DP vendor codec.
Not sure what is the technical motivation for this codec, but we can support it; at least the specs are public.
Implement also packet fragmentation for it, which needed some changes in a2dp-sink and a2dp-source.
Tested with bluez-alsa to both directions, also packet fragmentation. Actual hardware devices using this one seem hard to find.
See commits for details.