Design widget - Allow user to paste designs
### Summary
Offer the ability for users to paste designs to design management, as previously allowed on the legacy design widget.
### Proposal
* Allow paste to the design management widget based on following:
* Work item detail page or detail drawer is in view/focus **AND**
* There is no comment/description (textarea) field in focus **AND**
* User uses the paste command **with a supported image type**
* Include focus state for the design widget (seen in design)
* When user tabs through page, entire design widget itself would be focused first, followed by it's interior focus elements.
* If user clicks on empty area within the design widget (ex: space around designs, empty space in header), focus the "outer" widget (first focus as discussed in previous point)
* For the image title upon upload, use the following format:
* `<filename>_<timestamp>(<duplicate number)`
* Ex: `image_2025-04-18_5.02.50(2)`
* I'm not sure if duplicate would be possible in this scenario, but including how we'd handle it in case this could occur.
### Resources
- :mag: [View in Figma](https://www.figma.com/design/6ybGCKby1SPqIsSB2p35GR/Work-Items---Design-Management?node-id=900-113635&t=dO02iEq1BdSIEqI7-1)
- Design Management Design issue: https://gitlab.com/gitlab-org/gitlab/-/issues/385195/
- Spike MR: https://gitlab.com/gitlab-org/gitlab/-/merge_requests/147989
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