1) When trying to D&D **from** a locked layer Krita will
   force a "copy" mode

2) When trying to D&D **into** a locked group the operation will
   be forbidden. If the user still managed to do that, the layer
   will be put into a new position.

3) Layer->Properties should not be allowed for locked layers or
   masks.

4) Layer->Convert should not be allowed for locked layers

5) Lower/Raise node should not move nodes in a locked group

6) Lower/Raise node should not try to enter a locked group

BUG:425412
BUG:406697

# Conflicts:
#	libs/ui/kis_layer_manager.cc
#	libs/ui/kis_mask_manager.cc