Investigate effort to refactor mirroring settings into Vue

Problem to solve

Since the latest update to this area, we've seen some bugs that hinder UX and frustrate users: https://gitlab.com/gitlab-org/gitlab-ee/issues/7320

We need to understand the concrete size of the effort to refactor this area into Vue, so that we can fix the problem and make this feature easy to use and manage.

Further details

• The main problem seems to stem from the fact that we don't show current settings and don't allow to edit them without delete.
• If this was a vue component, we could easily add an "edit" mode + a summary of current settings.
• With Vue we could also add more enhancements and make sure the UI always stays updated

Proposal

Assess all the moving parts of this screen and try to come up with a proposal for the Vue app, list of components, etc. so that we can easily scope the effort for an upcoming milestone.

What does success look like, and how can we measure that?

Able to estimate and define a plan to refactor this into Vue.

Links / references