[CoarseDropout] Make it work in a constrained region

[ternaus]

Like in a set of bounding boxes.

Say we want to make model robust to occlusions for a particular class, person, or ball.

[vedantdalimkar]

Hi @ternaus, I would like to work on this issue if possible.
I was thinking for this feature we can take a mask as an input, which will contain the class regions on which the user wants to apply CoarseDropout.

[ternaus]

I do not have clear vision, how to do it, but let's try way that you propose.

And let's not change CoarseDropout, but create a new transform with this functionality.