(#6749) string cli base: implement preinit CLI parsing

In order to identify the full set of options we need to know the action that
is being invoked; that actually requires a pre-processing step to identify
that out of the global options.

Notably, our spec is that options can be to the right of their declaration
point, but not to the left: that means that we can now extract the full set of
options, and interact with the standard Puppet option handling code, resulting
in at least vaguely saner behaviour...

Reviewed-By: Pieter van de Bruggen <pieter@puppetlabs.com>