Package Repo Cache

[christophenne]

Is your feature request related to a problem? Please describe.
We request some resources of the package repository quite often, these could be cached. In one case this has been implemented already, see here: #286 (comment) . But this served just as a temporary solution, and we want a solution that is easier to re-use for other repo caching purposes too.

Describe the solution you'd like

• Research caching solutions and libraries
• Implement caching for queries to the package repo for CLI commands and package operator.

Describe alternatives you've considered

Additional context

[kosmoz]

We now have a in-memory cache for the repo client (#381), which especially helps the serve command and package-operator to perform much less requests.

To improve this even further, we should investigate implementing a shared on-disk cache.