Resolve "Allow multiple screenshots to be uploaded in copy paste"

What does this MR do?

When we copy/paste a screenshot to the Designs tab, it has a generic name of image.png. This might prevent uploading a few screenshots in a row. This MR renames image.png to design_<timestamp>.png to prevent overriding screenshots on any subsequent upload.

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Database guides
• Separation of EE specific content

Availability and Testing

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.
• Tested in all supported browsers
• Informed Infrastructure department of a default or new setting change, if applicable per definition of done

Issue #214470 (closed)