Window for listing all clipping masks used in project

Ran_TH

Given that most Live2D models today uses extensive amount of masks, adding a window for listing all clipping mask in one project can be very useful. Sometimes we lost track which parts has mask applied on them, which makes model optimization harder in case we want to reduce the amount of masks.

The window should be similar to "Deformer Validation" window, where it lists the masked object on one column and its corresponding clipping object in other column. Would be great if clicking the row would automatically select the clipped objects, similar to recent version "Select clipping masks objects" button does.