meson: add a video codec support option

This allows to turn on/off all hw implementations for a specific video
codec across the tree. Patent encumbered codecs can cause problems for
distributions due to the nature of at least MPEG-LA licensing.

https://jina-liu.medium.com/settle-your-questions-about-h-264-license-cost-once-and-for-all-hopefully-a058c2149256
is probably the best explaination I can find.

From a distro pov, codecs are a jigsaw puzzle, you only seem to become a problem well you fit all the pieces.

This patch will allow disabling the mesa piece of the puzzle.

Reviewed-by: Dylan Baker <dylan@pnwbakers.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/15258>