With all apps and modules/plugins porting itself to libsoup3 we also need to do so.
It would appear as a good idea to conditionally import "3.0" and fallback to "2.4"
bindings here, but its not as loaded GStreamer plugins might use libsoup3 already
and we cannot have both libsoup2 and libsoup3 in a single process.
Initializes GStreamer library and tweaks some of its defaults to our liking.
This also allows usage of GstClapper API alone without importing GStreamer on the implementation side.
It changes preferred hardware acceleration order (depending on plugins versions) into:
v4l2sl -> nv -> va -> vaapi -> v4l2
The "clapper_src" directory name was unusual. This was done to make it work as a widget for other apps. Now that this functionality got removed it can be named simply "src" as recommended by guidelines.
