Add opus decoding support to the web UI

[Aitolda]

Our servers already support opus encoding, but at the moment vircadia web is delivering uncompressed raw audio. There is currently a noticeable delay. while decoding will ad it's own bottleneck, the reduction in filesize might be more significant to said delay.

"Opus has the low algorithmic delay (26.5 ms by default) necessary for use as part of a real-time communication link, networked music performances, and live lip sync; by trading-off quality or bitrate, the delay can be reduced down to 5 ms."