[Feat]: log context for slow responses

[mikemccracken]

Is your feature request related to a problem? Please describe.

We have seen a couple of instances where zot responds very slowly to GET requests (whatever skopeo inspect generates) - a query that usually returns in < 1 sec would take many minutes. We could guess at the cause, maybe some background processing slowed things, but there were no errors logged.

Describe the solution you'd like

It would be useful to have a threshold time for a request, after which zot logs some useful info to help discover performance issues.

Describe alternatives you've considered

No response

Additional context

No response