Remove glib and gobject dependencies everywhere

They are part of gst_dep already and we have to make sure to always have
gst_dep. The order in dependencies matters, because it is also the order
in which Meson will set -I args. We want gstreamer's config.h to take
precedence over glib's private config.h when it's a subproject.

While at it, remove useless version and fallback args for gmodule/gio
dependencies, only gstreamer core needs it.