feat(ui): cache mask images, fix viewer getting stuck bug

[psychedelicious]

Summary

Two changes:
feat(ui): cache control layer mask images

When invoking with control layers, we were creating and uploading the mask images on every enqueue, even when the mask didn't change. The mask image can be cached to greatly reduce the number of uploads.

With this change, we are a bit smarter about the mask images:

• Check if there is an uploaded mask image name
• If so, attempt to retrieve its DTO. Typically it will be in the RTKQ cache, so there is no network request, but it will make a network request if not cached to confirm the image actually exists on the server.
• If we don't have an uploaded mask image name, or the request fails, we go ahead and upload the generated blob
• Update the layer's state with a reference to this uploaded image for next time
• Continue as before

Any time we modify the mask (drawing/erasing, resetting the layer), we invalidate that cached image name (set it to null).

We now only upload images when we need to and generation starts faster.

fix(ui): fix viewer getting stuck when spamming toggle

Related Issues / Discussions

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QA Instructions

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Merge Plan

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Checklist

• The PR has a short but descriptive title, suitable for a changelog
• Tests added / updated (if applicable)
• Documentation added / updated (if applicable)