List multiple clusters

What does this MR do?

Adds support for listing kubernetes clusters in a project.

Frontend

• Add empty state
• Add illustration - Needs to be updated. Needs the svg dependency to be updated. Can be done outside this MR.
• Add responsive tabs
• Add counters to tabs
• Add "add cluster" button
• Add responsive table
• Add toggle button
• Handle toggle button click to send request to API
• Add loading state to toggle button
• Add pagination
• Handle errors
• Handle JS unit tests
• Handle e2e tests

Are there points in the code the reviewer needs to double check?

N/A

Why was this MR needed?

N/A

Screenshots (if relevant)

	Screen_Recording_2017-11-24_at_07.23_PM	Screen_Recording_2017-11-24_at_07.29_PM

Does this MR meet the acceptance criteria?

• N/A Changelog entry added, if necessary
• Documentation created/updated
• N/A API support added
• Tests added for this feature/bug
• Review
  • Has been reviewed by UX
  • Has been reviewed by Frontend
  • Has been reviewed by Backend
  • N/A Has been reviewed by Database
• Conform by the merge request performance guides
• Conform by the style guides
• Squashed related commits together
• Internationalization required/considered

What are the relevant issue numbers?

https://gitlab.com/gitlab-org/gitlab-ee/issues/3734