feat(ui): support pasting directly to canvas

[psychedelicious]

Summary

When the user pastes into the browser under these conditions...

• Clipboard contains a single image file which passes our upload validation
• Canvas tab is active
• Viewer is closed

... we present the user with a modal asking where they should paste to:

Related Issues / Discussions

Offline discussion

QA Instructions

Try it out.

Merge Plan

n/a

Checklist

• The PR has a short but descriptive title, suitable for a changelog

[hipsterusername]

This will need restyling before it can be merged.

[psychedelicious]

Ok, how about this:

[hipsterusername]

Feels like we need some form of visual

Have we sworn off any custom icons?

[psychedelicious]

Custom icons take a lot of time to create and format to work in the app. Especially if you want it to match with all the other icons. I don't think that's something we should be spending time on.

Btw it's not pasting "in" the bbox. You could be pasting something much larger than the bbox and we aren't going to resize it. It's pasting at the bbox.

[hipsterusername]

Open to ideas on icons that fit the bill. Just needs something.

“in Bbox” vs “At Bbox” is semantics I don’t think users will necessarily have issues with but also think either is fine.

[psychedelicious]

Ok how's this?