Migrations for adding issue_id to versions table (EE)

What does this MR do?

This is the EE backport for the migrations in https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/30765. It includes some small changes to DesignManagement::Versions to specify the new unique scope for sha, and allow saving an issue for a Version.

Issue #11090 (closed)

Does this MR meet the acceptance criteria?

Conformity

• [-] Changelog entry
• [-] Documentation created/updated or follow-up review issue created
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Database guides
• Separation of EE specific content

Performance 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