monitor: cleanup parsing of cmd name and cmd arguments

monitor: cleanup parsing of cmd name and cmd arguments

There's too much going on in monitor_parse_command().
Split up the arguments parsing bits into a separate function
monitor_parse_arguments(). Let the original function check for
command validity and sub-commands if any and return data (*cmd)
that the newly introduced function can process and return a
QDict. Also, pass a pointer to the cmdline to track current
parser location.

Suggested-by: Markus Armbruster <[email protected]>
Signed-off-by: Bandan Das <[email protected]>
Acked-by: Luiz Capitulino <[email protected]>
Signed-off-by: Markus Armbruster <[email protected]>