This aims to be a replacement for the GstPlayer library. In GstPlay, notifications are
sent as application messages through a dedicated GstBus. The GMainContext-based
signal dispatcher was replaced by a GObject signal adapter, now relying on the
bus to emit its signals. The signal dispatcher is now optional and fully
decoupled from the GstPlay object.
Co-authored with: Philippe Normand <philn@igalia.com>
Fixes#394
Part-of: <https://gitlab.freedesktop.org/gstreamer/gst-plugins-bad/-/merge_requests/2061>