h265parser: decouple GstH265Profile and GstH265ProfileIDC

h265parser: decouple GstH265Profile and GstH265ProfileIDC

We used to have the same enum to represent H265 profiles and idc values.
Those are no longer the same with extension profiles defined from
version 2 of the spec.
Split those enums so the semantic of each is clearer and we'll be able
to add extension profiles to GstH265Profile.

Also add gst_h265_profile_tier_level_get_profile() to retrieve the
GstH265Profile from the GstH265ProfileTierLevel. It will be used to
implement the detection of extension profiles.

https://bugzilla.gnome.org/show_bug.cgi?id=793876