Support for more complex field selector filtering

[Iceber]

The current filter selector supports filtering on fields and values (eg. --filter-selector="spec.replicas=1"), but in some cases we need to compare two fields within a resource.
eg. --field-selector="spec.replicas == .status.readyReplicas"

Currently, when comparing between two fields, it looks like it needs to support only == and !=.
There is also the question of how to better distinguish between field comparisons and field-value comparisons.