[WIP] Add list cmd for Pulsar Functions

[wolfstudy]

Add list cmd for Pulsar Functions

USED FOR:
    List all Pulsar Functions running under a specific tenant and namespace.

REQUIRED PERMISSION:
    This command requires super-user permissions.

EXAMPLES:
    #List all Pulsar Functions running under a specific tenant and namespace
    pulsarctl functions list
	--tenant public
	--namespace default

OUTPUT:
    #normal output
    +--------------------+
    |   Function Name    |
    +--------------------+
    | test_function_name |
    +--------------------+

Usage: pulsarctl functions list [flags]

Aliases: list, list

FunctionsConfig flags:
      --tenant string      The tenant of a Pulsar Function
      --namespace string   The namespace of a Pulsar Function