Resolve "Operations Homepage MVC"

What does this MR do?

This is the first MVC iteration of operations dashboard.

See https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/7973 for frontend code

What are the relevant issue numbers?

Closes #5781 (closed)

https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/22136

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Documentation created/updated
• Tests added for this feature/bug
• Conforms to the code review guidelines
• Conforms to the merge request performance guidelines
• Conforms to the style guides
• Conforms to the database guides
• EE specific content should be in the top level /ee folder
• For a paid feature, have we considered GitLab.com plans, how it works for groups, and is there a design for promoting it to users who aren't on the correct plan?

TODO

Frontend

• Add Operations Dashboard UI
• Add unit tests for all newly created components
• Add 'Add projects' by link functionality
• Modify Ellipsis text color to lighter gray on project header

Backend

• Mock /-/operations/list
• Expose endpoints as data attributes in #operations div container
  • add-path
  • list-path
  • remove-path
• Real /-/operations/list
  • Real last_deploy - (last deployment named production)
  • Real alerts ⬅ !7493 (merged)
• Handle empty (null) avatar_urls
  • ➡ Client handles all of this
• Default dashboard
  • Allow "Operations dashboard" to be configured as default dashboard
  • EE only
• Add projects
  • Create users_dashboard_ops_projects
  • Check permission on adding and viewing projects (developer or above)
• Remove project
• Check licensed feature
• Translations