Implement cluster environment and domain form using VueJS

Problem

The cluster view page is implemented using a mix of Rails and Vue:

UX improvements, like gitlab-ce#57357, require the Rails part of the cluster page to be updated based on the state changes captured by the Vue part. This leads to writing code that does not reflect our coding best practices: https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/26124/diffs#80f848020d4e29fdb91bd4f9afb42ac3a6069eac_280_291

Solution proposal

Integrate the "cluster environment and cluster domain" form with the cluster applications Vue app. In that way, we can avoid direct DOM mutations and other solutions that make this feature more difficult to maintain.