[Frontend] Mark an endpoint as down only when its unreachable

[ghost]

This feature request is for the UI changes that are required to implement #2940

Is your feature request related to a problem? Please describe.
If an aspect of a snapshot fails e.g volumes cannot be fetched then the endpoint is marked as down, even though I can still access it and issue Docker commands.

Describe the solution you'd like
During snapshot of an endpoint; If the ping succeeds but a Docker command fails don't mark the endpoint as down, but change the label to 'incomplete info' or 'partial snapshot' on the endpoint.

• Could also possibly show aspects such as volumes being 'NA' if this info is not available.
• When in the partial snapshot view, clicking on view X should show X is not available in this partial snapshot or something similar

Example of these proposed changes