Add `dopr --list` to list all registered actions

[adhocore]

Not a functionally useful feature but for favor of better UX and a quick doc preview, just provide a helpful list of registered actions and short description (where available)

[wmathes]

the idea is basically printing out all available commands? :)

what about the dynamically mapped default commands?

[adhocore]

ya all action keys within "actions" included :D