Support Aggregated Discovery API

[DanielShaulov]

Since k8s 1.30, Aggregated Discovery API is available and enabled by default.
It would be nice if Discovry::run could support this (optionally) to reduce the amount of API calls.

[clux]

Ah, thanks for raising this. This would indeed be good to have. I might try to spend some time on this soon to see if it has potential to simplify some stuff (which by the sounds of it, it could have).