Move codeowner validation checks into Commits::CreateService

What does this MR do?

Iteratively, we've pushed these checks into a number of different locations, however having a unified, single-location for these checks is for more sustainable into the future. By moving the existing "web request" checks into Commits::CreateService, we can remove the existing checks previously added to the file editor, enable checks on the Commits REST API (create/update/delete, cherry-pick, revert), and can remove the :skip_web_ui_code_owner_validations ermergency workaround

Testing

This change has passed automated tests for existing Code Owners scenarios, as well as manual QA testing:

Basic setup steps before testing:

1. Create a repo on your development instance
2. Enable code owners on a protected branch (master is fine)
3. Create README.md , editable.md, and test/ directory
4. Create a CODEOWNERS file with entires for README.md and test/ . Assign one to your account’s @ name, and the other to both you and 2nd user in the app.

File Editor

• Against file matching CODEOWNERS
  • Create new file — Expected: 🚫
  • Edit existing file — Expected: 🚫
• Against file NOT matching CODEOWNERS
  • Create new file — Expected: ✅
  • Edit existing file — Expected: ✅

Web IDE

• Against file matching CODEOWNERS
  • Create — Expected: 🚫
  • Edit — Expected: 🚫
  • Delete — Expected: 🚫
  • Rename — Expected: 🚫
• Multiple files, one matching CODEOWNERS
  • Create — Expected: 🚫
  • Edit — Expected: 🚫
  • Delete — Expected: 🚫
  • Rename — Expected: 🚫
• Against NOT file matching CODEOWNERS
  • Create — Expected: ✅
  • Edit — Expected: ✅
  • Delete — Expected: ✅
  • Rename — Expected: ✅

CLI

1. Clone locally
2. Change a file on a protected branch
3. Push change to gitlab

• On a protected branch
  • Commit contains a file that matches ANY rule in CODEOWNERS — 🚫
  • Commit does NOT contain a file that matches a rule in CODEOWNERS — ✅
• On an unprotected branch
  • Commit contains a file that matches ANY rule in CODEOWNERS — ✅
  • Commit does NOT contain a file that matches a rule in CODEOWNERS — ✅

API

Existing tests in

• spec/requests/api/commits_spec.rb
• ee/spec/requests/api/commits_spec.rb

Create commit

post ':id/repository/commits'

• Create action
  • Commit contains a file that matches CODEOWNERS — 🚫
  • Commit does NOT contain a file that matches CODEOWNERS — ✅
• Update action
  • Commit contains a file that matches CODEOWNERS — 🚫
  • Commit does NOT contain a file that matches CODEOWNERS — ✅
• Delete action
  • Commit contains a file that matches CODEOWNERS — 🚫
  • Commit does NOT contain a file that matches CODEOWNERS — ✅

Cherry Pick

post ':id/repository/commits/:sha/cherry_pick'

• Commit contains a file that matches CODEOWNERS — 🚫
• Commit does NOT contain a file that matches CODEOWNERS — ✅

Revert

post ':id/repository/commits/:sha/revert’

• Commit contains a file that matches CODEOWNERS — 🚫
• Commit does NOT contain a file that matches CODEOWNERS — ✅

Merge Requests

MR contains protected file

• Approval rule created
• Approval rule displays any/all users listed in the entry

Once approval rules are satisfied

• User with merge rights can successfully merge regardless of code ownership

Misc

• blocks file uploads to protected

Addresses #218687 (closed)