Add new Websocket Handler, add Project Add Listener

src/main/scala/de/tobias/playpad/server/PlayPadServer.scala

...main/scala/de/tobias/playpad/server/account/Account.scala

...aypad/server/server/project/sync/ProjectSyncHandler.scala

...laypad/server/server/project/sync/listener/Listener.scala

...er/project/sync/listener/project/ProjectAddListener.scala