Resizing something that has drag handles causes each individual resize to go onto the undo stack

[city41]

repro:

1. add a conveyor belt to a level
2. using its drag handle, drag it to be really long, then really short, then let go
3. press undo

expected: the conveyor belt returns to its original size before any dragging happened

actual: each one tile change in size gets recorded as an action, so you have to press undo many times to get the conveyor belt back

NOTE: this should be easy to do by adding a group for resize events in editorSlice