smb-notifier: do not send remove events on moving files

windows (but not samba interestingly) will send a REMOVE event before
the actual MOVE event this would mess with kio's dirlister's internal
state as it'd remove the file from the model and then never try to learn
about it again when it receives the move event. effectively this would
remove a file from the view in dolphin when renaming it as now both the
old name and the new name aren't in the dirlister model anymore.

to prevent this from happening a similar hack is applied to the event
order as with move merging.

when a remove arrives it's not immediately emitted but queued for up to
1000ms if a move event also arrives during that time frame the remove is
entirely discarded and we are left with only the move.
if any other event arrives the remove is immediately sent.
if nothing else arrives the timer runs out and the remove is sent.

so worst case a remove is only represented in the GUI after 1s, best
case it's more or less same as before with the added benefit that
renaming doesn't make files disappear

CCBUG: 430585