feat: Food for thought for the new API CLI design [WIP]

[netmilk]

DISCLAIMER: This is not a final PR but a DRAFT to have conversation over.

I have transformed @barjin's initial proposal and notes from our session into a man page mock. It's just food for thought. There might be lots of factual discrepancies; this aims to get feedback as early as possible.

My primary adjustment is that I prefixed the slightly controversial run and actor namespaces to relieve the overload of the term "run" and to set clear expectations on the remote or local execution. The actor namespace is then dedicated solely to the actor-related commands as described in the actor-spec

I'm not super happy with the prefixes, but the other options are:

• break the actor run backward compatibility
• go for plurals runs, actors, datasets, etc.