`layer_used` runtime data, which controls the drawing of dots in the UI was not getting refreshed properly.
This used to happen in the drawing code, but was no longer working for reasons explained in:
{rB2b09062defa093a243b5fe64b099accb07b440a3}
The solution was to update each layer manually in the operators:
* ARMATURE_OT_bone_primitive_add
* ARMATURE_OT_delete
* ARMATURE_OT_dissolve
* ARMATURE_OT_fill
* ARMATURE_OT_merge
* ARMATURE_OT_separate
* ARMATURE_OT_bone_layers
* POSE_OT_bone_layers
Differential Revision: https://developer.blender.org/D5281
709f126e81