libs: encoder: get surfaces resolution the same time with formats.

libs: encoder: get surfaces resolution the same time with formats.

We can get all the information about the video format at one shot
when we create the test context for getting the supported formats.

The current way to get the width and height ranges are inefficient,
since it calls the function gst_vaapi_profile_caps_append_encoder()
and it creates another temporal context to detect the resolution
information.

Signed-off-by: Víctor Manuel Jáquez Leal <vjaquez@igalia.com>