Link Branch Rules Overview from CODEOWNER file to require approval

Problem

When users where asked to change the settings so that CODEOWNERS approval was required many spent a lot of time looking at the CODEOWNERS file itself and its documentation: recording of the research outcomes / CM Scorecard Recommendations - Create:Source Co... (gitlab-design#1374 - closed)

Proposal

When viewing the CODEOWNERS file add a hint that requiring CODEOWNERS approval can be set under Branch Rules and link to the Overview page.

More advanced: when viewing the CODEOWNERS file surface which branches currently require their approval and link to the Branch rules for changing the rules.

Design

• Add button "Manage branch rules"
  • Click navigates user to Branch rules overview in "Settings > Repository"
  • Text: Manage branch rules
  • Size: sm
• Button only appears for users who have permission to view settings

Scenario	Design
No code owners defined
Code owners defined

Links

• Figma: https://www.figma.com/file/eq2nf3B8MhB9xKrC0VzbPf/Repository?node-id=42%3A100623&t=EQ6TSCex0n3tIUjm-1

Availability and Testing

Feature spec to be added for:

• button to jump to settings
• listing code owners
• no code owners message