Implement `dnd-kit` for image drag and drop
- vastly simplifies logic bc we can drag and drop non-serializable data (like an `ImageDTO`)
- also much prettier
- also will fix conflicts with file upload via OS drag and drop, bc `dnd-kit` does not use native HTML drag and drop API
- Implemented for Init image, controlnet, and node editor so far
More progress on the ControlNet UI
* added optional middleware prop and new actions needed
* accidental import
* make middleware an array
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Co-authored-by: Mary Hipp <maryhipp@Marys-MacBook-Air.local>
