Add ORTC Media examples

[Sean-Der]

RTPSender and RTPReciever exist, now we just need examples of how to use them

[backkem]

This also requires (to do it correctly anyway):

• RTCRtpSender.getCapabilities
• RTCRtpReceiver.getCapabilities
• ORTC also leaves figuring out common codecs to the API user. We would need something like: https://draft.ortc.org/#x19-3-determining-common-capabilities. We probably need this logic in the WebRTC API somewhere as well. We can port the logic used in webrtcHacks/adapter.

[Sean-Der]

This is blocked because we don't have an easy way to send video currently.

When we have IVFReader and OpusReader this will be trivial to implement!