Button to switch off Dashboard

[NikCanvin]

In a discussion with @sam-github, we decided we needed to offer a capability to switch-off the dashboard. This is a one-way action, once off, the dash board can't be restarted without restarting the parent Application.

Use case: An Application Owner deploys their App, with or without knowledge that the Dashboard automatically displays metrics (we expect some Offerings bundling appmetrics-dash, to seamlessly require/start monitoring, so the App Owner may not even know about it)... Then when the App is in production they decide they want to Turn off the dash board URL without interrupting their App in production.

[sam-github]

I don't recall that, I don't object, but the supervisor already supports this via cluster rolling restart with a new environment.

Would it be just the dashboard, or appmetrics as well?