give maxctrl its own installation package

as of today, to run scripts that interrogate a remote maxscale instance we either have the choice to install the full maxscale or to rely on curl.

that would be pretty handy to have to ability to install just maxctr, the same way the mariadb CLI.

ofc when installing maxscale, ther would be a dependency so that it automaticalkly installs the maxctrl packaghe as well.