aja: Prepare plugins for new libajantv2 repo

Support building AJA plugins with either the new libajantv2 library, or
the deprecated ntv2 library.

Finder scripts updated to search for libajantv2 and fall back to ntv2 if
not found. This allows this PR to be merged without requiring a
corresponding update to the pre-built obs-deps packages.
This commit is contained in:
Internal Server Error - Gitea: Git with a cup of tea
500 Internal Server Error

Gitea Version: 1.28.0+dev-477-g8b6ad49a5f