enh(viz): merge undo point and undo region in freehand crop
Description
Make the "undo" easier to understand in freehand crop by merging undo point and undo region in one action.
Proposal
Do the test in the service:
if region is already computed: undo the last region. else: undo the last point.
Functional specifications
Simplify action related to freehand crop.
Technical specifications
Only one "reset" slot (?)
Test plan
Test on sight_viewer