Add isRemoved property to show entity.
Update endpoints source.

- Only update Show this time.
Do not auto-add shows flagged as removed on Hexagon.
Set isRemoved flag on Hexagon when deleting show.
So null Boolean do not default to false in conditions, well...
Sync shows flagged as removed, just do not auto-add them.
Unify log message for trakt credentials check.
If show was added successfully, remove isRemoved flag on Hexagon.