When the SPS associated with a particular SPS ID changes, invalidate all
the PPSs which use that SPS ID.  Fixes crashes with illegal bitstreams.
This is done in the CBS, rather than in libavcodec/vvc/ps.c like the SPS
ID reuse validation, as parts of the CBS parsing process for PPSs
depend on the SPS being referred to.
Signed-off-by: Frank Plowman <post@frankplowman.com>