Generalize toggle_buttons for JavaScript usage

What does this MR do?

EE MR, https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/4244

No functional changes to the UI

• Generalize toggle_buttons for JavaScript usage
  • There were two separate implementations for the cluster list and cluster edit page
  • We also need this for the dynamic variable list, https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/4110

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

• There is already toggle_button.vue but it is Vue focused. We could instantiate a Vue component for each instance but requires external handlers to change the state and isn't consistent with the rest of the code around it. Update: I created a separate version of this MR with this strategy, https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/16698

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
  • Not a user-facing change
• Tests added for this feature/bug
• Review
  • Has been reviewed by Frontend
• Conform by the merge request performance guides
• Conform by the style guides
• Squashed related commits together
• Internationalization required/considered
• End-to-end tests pass (package-qa manual pipeline job)

What are the relevant issue numbers?