Revert "Handle gstreamer signals on main QGC thread to avoid deadlock; Remove video sink from pipeline if pipeline failed to start"

This reverts commit a9401de7.

Handle gstreamer signals on main QGC thread to avoid deadlock; Remove video sink from pipeline if pipeline failed to start

Fix matroskamux stream start (workaround for https://gitlab.freedesktop.org/gstreamer/gst-plugins-good/issues/449)

Use parsebin for automatic stream demuxing and parsing; Automatically insert rtpjitterbuffer for RTP streams to avoid video stuttering

Switch to decodebin and use decoder with highest rank; Use GL context provided by qmlglsink; Fix JNI code for AndroidMedia initialization

Signed-off-by: Patrick José Pereira <patrickelectric@gmail.com>

This solves the issue where the video is lost for a few seconds  after
clicking record as the filesink attempts to preroll but doesn't have a valid buffer,
stalling the whole pipeline.

Updated MAVLink to handle video stream types (auto discovery)