[CLI-2030] hide kafka quota, pool, provider, stream-share cmds when feature flag not enabled

[MuweiHe]

Checklist

1. [CRUCIAL] Is the change for CP or CCloud functionalities that are already live in prod?
   • yes: ok

What

Users caught that they are still able to run confluent iam provider list (with or without an error) even though the flag is not enabled and hid from its parent command. see: https://confluentinc.atlassian.net/browse/RCCA-9133.This pr makes those feature flag controlled commands not executable when not available.

// when not enabled
mhe@C02DV0KVMD6T cli % confluent ss
Error: unknown command "ss" for "confluent"
Run 'confluent --help' for usage.

// when enabled
mhe@C02DV0KVMD6T cli % confluent ss
Manage stream shares.

Usage:
  confluent stream-share [command]

Aliases:
  stream-share, ss

Available Commands:
  consumer    Manage consumer actions.
  provider    Manage provider actions.

References

Test & Review