Resolve "Improve format support message in issue design"

What does this MR do?

On uploading a wrong file format, we have shown a generic error: Error uploading a new design. Please try again.. This MR replaces it with more specific error returned from the BE in errors field.

Screenshots

Before	After

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 #210339 (closed)