New shortcut to set and get build config.

[floooh]

fips config xxx should be a shortcut for fips set config xxx, and fips config should print the currently selected build config (instead of fips list settings).

cc @gustavolsson

Existing functionality won't break, these are just additional shortcuts for two very common actions.

[gustavolsson]

Another idea, what about fips switch config or fips prev config to switch to the previous config? That way one can switch between 2 different configs easily..

[floooh]

...that's a bit too much "do what I mean" for my taste ;)

On Mac and ~~Windows~~ Linux, shells with a fish-shell-like context-sensitive history provide most of that already (e.g. when I type "./fips set co" I can cycle through the recent "./fips set config ...." I did in that directory with the up-arrow key).

Not sure if there's some equivalent for Windows...