When swapping between several development branches, compilation times can be
frustrating. This commit proposes adding features to control which signaller
to include when building the webrtc plugin. By default, all signallers are
included, just like before.
Compiling the `webrtc-precise-sync` examples with `--no-default-features`
reduces compilation to 267 crates instead of 429 when all signallers are
compiled in.
Part-of: <https://gitlab.freedesktop.org/gstreamer/gst-plugins-rs/-/merge_requests/1539>
Implement new signaller WhipServerSignaller
- an http server using 'warp'
- handlers for the POST, OPTIONS, PATCH and DELETE
- fixed path `/whip/endpoint` as the URI
- fixed value 'whip-client' as the producer peer id
- fixed resource url `/whip/resource/whip-client`
Derive whipserversrc element from BaseWebRTCSrc
- implement constructed method for ObjectImpl to set
non-default signaller, i.e., WhipServerSignaller
- bind the properties stun-server and turn-servers to those on
the Signaller
Connect to 'webrtcbin-ready' signal in the constructor of WhipServerSignaller
- it will be emitted by the webrtcsrc when the webrtcbin element is ready
- the closure for this signal will in turn connect to webrtcbin's ice-gathering-state
and perform send with the answer sdp via the channel
- the WhipServer will hold its HTTP response in POST handler until this signal
is received or timeout which happens early
Part-of: <https://gitlab.freedesktop.org/gstreamer/gst-plugins-rs/-/merge_requests/1284>
