Move design management app to the issue tab

What does this MR do?

This MR implements moving a design management application to the Issue description behind the feature flag. If you want to test changes locally, please be sure to run the following code in the Rails console:

Feature.enable(:design_management_moved)

Please be mindful this MR doesn't include changes to visual styles, it just moves the application, fixes routing and updates specs. You can see the roadmap for planned changes below

Change	MR
Create a new Design Management app to be displayed behind the feature flag	!34932 (merged)
Refactor Design Management app to be displayed on the Issue instead of tabs	👉🏻 You are here
Refactor Design management application to match new visual styles	TBD
Update Design Management documentation	TBD
Make a cleanup after Design Management feature flag is removed	TBD

In addition, I've replaced local appData query with provide/inject approach.

Screenshots

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

Closes #223193 (closed)