Operator to make all or selected layer images blank

[ucupumar]

Pre-Flight checklist

• [x] Did you check to see if this issue already exists?
• [x] This is a single feature request. (Do not put multiple feature requests in one issue)

Describe The Feature Request Below

Duplicate blank already exists, but it can also be useful if there's an operator to make all images used in the selected layer or all layers go blank.