Enable Maintenance Control from the UI

**New UI**
Using the latest UI

**Describe the problem you're having**
Our automation disables maintenance mode once a service is back up and healthy but sometimes this fails and a node is actually healthy but we are still in maintenance mode even though it is ready to be accepting traffic. I'd like to be able to disable maintenance mode from the UI instead of going to each individual node and disabling. Having the enable option here too makes sense but I could see an issue with having it there for users.

**Describe the solution you'd like**
I would like to be able to control maintenance mode for a node from the UI.

The issue does not mention any files, tests, or entry points, so start by locating the existing UI for per-node maintenance mode and its corresponding control path. Done means a user can control a node's maintenance mode from the UI without visiting each individual node; clarify whether enabling it is also required.

Written by the indexing model from the issue text.