feat: make kopium usable as a library

[the-wondersmith]

PR makes kopium usable as a library in addition to its current standalone tool status.

Addresses #335

[clux]

hey, thanks for the showcase for this. it's a decent start.

i'm not keen on just exposing most of main as a library interface though. arg parsing / stdin reading / auto complete / crd detection etc is not really a lib concern.

i am open to refactors that lifts stuff from main into the output module (or some similar formatter moduler) because then the already published library (e.g. the one with docs here) would be more useful.

also, file renames and large shifting around like this is also not great because this means i have a very hard github diff to review. kind of github problem and not yours, but i work with what's here 😢

[the-wondersmith]

@clux Would it be uhh.. keener to extract everything that isn't parsing / stdin reading / auto complete / crd detection to the lib level then? Happy to take a second pass at it.

[the-wondersmith]

@clux took that second pass and separated all the "clearly CLI" from "probably library" code. Hopefully it's closer to spec?