transport: Don't put a capsfilter after the audio decoder and link the depayloader

We can't just force the audio decoder to output something specific, this will
fail with most audio decoders out there... and if conversion is required we
will do that later already.

Also make sure the pad that is ghosted is the decoded_valve and not the
capsfilter, which is incorrect.
OwrMediaRenderer: fix refcount bug in owr_media_renderer_set_source
sdp: Allow a=rtcp address to be optional

In accordance with RFC 3605
bridge: Don't assume mdesc.rtcp exists when checking mdesc.rtcp.mux
domutils: Use the expected variable name
webrtc_js: Avoid assigning the same property twice
peerhandler: Set the TURN server transport type from the iceServer URL

In accordance with RFC 7065
Add test utilities

Run ./out/<platform>/bin/test-self-view after building to run a simple
audio/video capture and output test.

Run ./out/<platform>/bin/test-send-receive after building to run a test
with one sender and one receiver in the same application.
Update scripts

Various build fixes.
sdp.js: Check presence of msid and mstid before generating msid line
OwrMediaSession: Run object signal handler in cleanup stage

For on-incoming-source
tests: Use a sane default resolution in test-send-receieve
local: Make video test also have a time overlay

Useful for debugging
tests: Set sane resolution for test-self-view