turn into a library, merge with Lighttouch, & use common Speakeasy CLI mechanism

[naturallymitchell]

https://github.com/foundpatterns/lighttouch/tree/master/keys
https://github.com/lighttouch-packages/keys

should match plans and recent progress from Gut in preparation for transition CLI to use https://github.com/foundpatterns/speakeasy/issues/10 and jazzdotdev/flute#144

[naturallymitchell]

this would make for a good, simple app to design a CLI crypto app

model: witness, file
rule: if the inputted file matches a friend's key, then respond 200
CLI commands: pretty basic...