MINOR: filters: Expose classes and instances through the CLI

MINOR: filters: Expose classes and instances through the CLI

Add operator-level commands to inspect the request/response class order,
list a proxy's flat instance order, and inspect a single instance by
class and optional id. Display its enabled and implicit/inherited state,
source location, sides and raw arguments.

Keep these diagnostics separate from the configuration and ordering changes.
They report the new instance model, not the still-legacy stream evaluation
path. This completes the split of the current WIP without changing its final
source contents or completing runtime integration.