View data freshness when serving cached responses

[JohannesRudolph]

Is your feature request related to a problem? Please describe.
Collie can serve some requests out of its cache. This is cool to quickly format reports, esp. when building automation pipelines. However it is difficult to know how "fresh" the data is that collie served (even though there are upper bounds due to cache experiation)

Reach of the feature request
Everyone using features where caching is very relevant (esp. the cost collection features I think).

Impact of the feature request
Not knowing how old data is can be a source of problems.

How would a solution look like?
The interactive output of most commands already presents info how quickly data was retrieved and whether it was from cache. Add additional meta data to this indicating how old the data of the cache is.

(optional) Implementation Hints
See above