Added the ability to see project deployments using a group cluster

Added a changelog entry for the feature

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

Add GKE, Login - HTML & CSS
Cluster details - HTML & CSS

- Moves toggle button to a shared location
- Adds tests for toggle button
- Transforms Clusters class into function
- Improves UX

Finishes tabs & table
Updates e2e tests

 - Split layout from the styles of the row
 - Move command `.append-` `.prepend-` styles to bottom of source order
    - Actually applies styles over others in more situations which is
      probably what is expected when you add it to an element
    - Also allows us to get rid of some styles that were trying to get
      around this fact

See https://i.imgur.com/IE50PK6.png
Which is used in
https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/15064

Design from https://gitlab.com/gitlab-org/gitlab-ce/issues/38464