Move features to Core: "Design Management""

What does this MR do?

To support the open source effort for these features, GitLab decided to move the premium/silver features that are being open-sourced down to the Free/Core tier immediately. This does not open source the features, but it does allow a wider audience to begin using them.

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
• Informed Infrastructure department of a default or new setting change, if applicable per definition of done

Security

This MR changes authorization of design management features so that they are more widely available. While the code remains in EE pending its move into core, the feature are made immediately available to any installation, with or without a license.

Closes #213136 (closed)