pbutils/h265: add support for the "format range extensions profiles" values

Submitted by Florent Thiery @florent.thiery

Link to original bug (#772584)

Description

gst-launch-1.0 videotestsrc ! "video/x-raw, format=(string)Y444" ! x265enc ! fakesink -v

gstx265enc.c(785): gst_x265_enc_set_level_tier_and_profile (): /GstPipeline:pipeline0/GstX265Enc:x265enc0:
Failed to find correct level, tier or profile in VPS

I saw this by trying to encode UYVY with an intermediate videoconvert; i am guessing that videoconvert prefers Y444 ti I420 to preserve data, but x265 apparently doesn't work with Y444

gst-launch-1.0 videotestsrc ! "video/x-raw, format=(string)UYVY" ! queue name=encoder ! videoconvert ! queue ! x265enc ! fakesink -v