NGF should not be processing resources it doesn't care about

[sjberman]

Describe the bug
NGF currently reads in every resource (Gateway, HTTPRoute, etc) in the system and stores in a map. It then filters the ones it cares about and builds a config. The problem with this is the CPU and memory usage will spike as many resources are created that are not relevant to us (they could be for other controller implementations).

Expected behavior
NGF should only be storing resources that are relevant to itself.