Config Sync API: Filter Packages in API

[jan-kantert]

Currently, we have to call curl -k -s -S -i -u root:icinga 'https://localhost:5665/v1/config/packages?pretty=1' (from https://icinga.com/docs/icinga-2/latest/doc/12-icinga2-api/#list-configuration-package-stage-files) to get the active stage for a package. However, when using a lot of packages this seems to be wasteful and slows down our Kubernetes Controller which handles one package at a time.

Describe the solution you'd like

We would like to be able to filter for one specific package (here in code: https://github.com/Icinga/icinga2/blob/master/lib/remote/configpackageshandler.cpp#L22).

Describe alternatives you've considered

Caching the response in our controller would be possible but not nice.