Add several log to trace the graph building
Register auto-load helper to accept ANY media type. PotPlayer seems to use only the first registered media type to load the auto-load helper, the second registered media type (audio) is NOT used and thus auto-load helper can NOT be loaded by audio tracks.
Do not reset auto-loading flag. PotPlayer manages two graphs at the same time. Auto-loaded XySubFilter will be inserted into the first graph and then be removed and then be inserted into the second graph. XySubFilter must get rid of VSFilter in both graphs.
Replace hard coded known source filter list with REG option. Read known source filter list from REG "KnownSourceFilter/giudX" for auto-loading check.
Add PotPlayer built-in MKV source filter to default known source filter list