Check which formats are supported by used GL context and filter them. This makes videoconvert always choose one of the supported by user hardware formats.
This MR moves supported GL formats init from glcolorconvert into private header, so it can be reused in glupload without duplicating code.
This change makes below pipeline work:
MESA_GLES_VERSION_OVERRIDE=2.0 GST_GL_API=gles2 gst-launch-1.0 videotestsrc ! video/x-raw,format=I420_10LE ! videoconvert ! glupload ! glcolorconvert ! glimagesinkelement