Option to apply baked layer/mask as standard image

[ucupumar]

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Describe The Feature Request Below

There's a case where users only want to bake AO/Edge Detect as a base for painting, so the rebake option becomes irrelevant. There should be an option to apply the baked layer/mask as a standard image layer/mask.

This becomes even more useful when baking any layer type is fully implemented (#65).