bug(ToggleComposites): Fix server delete composite handling

[Kruptein]

When moving shapes to a different location, the client sends which shapes to move and the server will move them and inform any client still on the old location which shapes to remove.

The server will check for each shape whether it's part of a toggle composite and move all variants along as well. It will also the variants to the list of shapes it sends to clients on the old location to remove.

The client however can sometimes also include the list of variants already in its original move request and the server was not handling this correctly, resulting in multiple requests to remove the same variants to be sent to some clients which would throw an error when they have to remove something a second time when it's already removed.

TL;DR The server now takes into account shapes already handled when moving them