verification/dot2k: Replace is_container() hack with subparsers

verification/dot2k: Replace is_container() hack with subparsers

dot2k is used for both generating deterministic automaton (DA) monitor and
generating container monitor.

Generating DA monitor and generating container requires different
parameters. This is implemented by peeking at sys.argv and check whether
"--container" is specified, and use that information to make some
parameters optional or required.

This works, but is quite hacky and ugly.

Replace this hack with Python's built-in subparsers.

The old commands:

  python3 dot2/dot2k -d wip.dot -t per_cpu
  python3 dot2/dot2k -n sched --container

are equivalent to the new commands:

  python3 dot2/dot2k monitor -d wip.dot -t per_cpu
  python3 dot2/dot2k container -n sched

Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Link: https://lore.kernel.org/23c4e3c6e10c39e86d8e6a289208dde407efc4a8.1751634289.git.namcao@linutronix.de
Reviewed-by: Gabriele Monaco <gmonaco@redhat.com>
Signed-off-by: Nam Cao <namcao@linutronix.de>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>