[pfcwd] Configuring to 'stop' ports

[d-dashkov]

- What I did
Refactored the pfcwd stop command to look like pfcwd start.
It provides an update to stop a specific port:
config pfcwd stop Ethernet0
Or for all ports at once:
config pfcwd stop all

fixes sonic-net/sonic-buildimage#6338

- How to verify it
Create pfcwd instances for ports:
pfcwd start --action drop Ethernet0 400
pfcwd start --action drop Ethernet80 400
show pfcwd config

Remove one port
config pfcwd stop Ethernet0
show pfcwd config

Or remove all of them
config pfcwd stop all
show pfcwd config

- Previous command input
config pfcwd stop

- New command input
config pfcwd stop <port name / 'all'>

[d-dashkov]

retest this please

[keboliu]

should use 'all' == ports?

[d-dashkov]

Such logic with the "in" statement should handle the case: "config pfcwd stop Ethernet0 Ethernet1 all" and remove all ports despite the first two arguments

[keboliu]

I don't think we need to support this kind of command: "config pfcwd stop Ethernet0 Ethernet1 all" seems strange to me.

[keboliu]

what will be the output of "config pfcwd stop --help" looks like?

[d-dashkov]

what will be the output of "config pfcwd stop --help" looks like?

admin@sonic:~$ sudo config pfcwd stop --help
Usage: config pfcwd stop [OPTIONS]

  Stop PFC watchdog

Options:
  --verbose       Enable verbose output
  -h, -?, --help  Show this message and exit.

[keboliu]

what will be the output of "config pfcwd stop --help" looks like?

admin@sonic:~$ sudo config pfcwd stop --help
Usage: config pfcwd stop [OPTIONS]

  Stop PFC watchdog

Options:
  --verbose       Enable verbose output
  -h, -?, --help  Show this message and exit.

I would suggest adding proper hint info about supported subcommand in the output