Backport of "qtdemux/mux: Drop av1C version 0 parsing and implement version 1 parsing/writing" into 1.20
Backport of !3882 (merged) "qtdemux/mux: Drop av1C version 0 parsing and implement version 1 parsing/writing".
Commits:
Backport of !3882 (merged) "qtdemux/mux: Drop av1C version 0 parsing and implement version 1 parsing/writing".
Commits: