cli: Rework interface so noun params are after verb

Change format from:
  fastpath [global opts] <noun> [noun opts] <verb> [verb opts]

to:
  fastpath [global opts] <noun> <verb> [noun and verb opts]

This allows us to more consistently use positional arguments (e.g. host
for sut noun, plan fil for plan noun, etc) and generally makes the
command simpler for humans to parse.

The noun still have one option; --help.

Implement by passing an add_noun_args() function from the noun's
add_parser() to the verb's add_parser().

Signed-off-by: Ryan Roberts <ryan.roberts@arm.com>