results: use subcommands instead of --action= option

[padovan]

We want the results cmd to look like kci-dev results summary instead of kci-dev results --action=summary , but we didn't figure out yet how to do that with Python Click.

Related to #57

[aliceinwire]

why don't use click choice options https://click.palletsprojects.com/en/stable/options/#choice-options
choice options looks like what you need to use instead of having a 'sub sub command' and it make it more clear, as summary is not really a sub command but a choice option
choice options also appear in the help file so that is clear what are the option that can be used

[aliceinwire]

I will send a draft with this

[aliceinwire]

Draft: #70