Take pending MyList updates into account when choosing the first unwatched file.

Take pending MyList updates into account when choosing the first unwatched file.

Pending MyList update changes are only written to the my_*
fields when a the UDP API confirms it's been set.
If the UDP API doesn't work for some reason firstUnwatchedByAid
will keep returning the same file until AniDB confirms the change.

To work around this, firstUnwatchedByAid now checks if a file isn't
queued to be marked watched right now (an update without a finished
time set). If it is, the file is treated as watched.

This only works in the simple case where a file is marked watched
by fid. It's the method MyList::markWatched uses. All other methods
aren't available outside of manually preparing a PendingMyListUpdate.