Implement Clean Architecture

[iibuan]

• [x] #1124
• [x] #1137

  • [ ] activity-types
  • [ ] activity-help

• [ ] communities
• [ ] community-approvers
• [x] contribution-areas
• [ ] categories
• [ ] category articles
• [ ] repositories
• [ ] users
• [ ] popular-topics
• [ ] approval-types
• [x] external-links
• [x] oss-contribution-sponsors
• [ ] other-requests
• [ ] organization-approvers
• [ ] legacy