Provide lucky init --edge support

One of the woes of installing lucky_cli from source is that, in order for lucky init to work properly, you must be on a tag.

I would be nice if the functionality of lucky init worked as such:

• lucky init always yields an app checked out from $LATEST_TAG of all respective repos
• If a user passes an --edge flag, lucky init uses branch: main for all lucky deps

We might be able to look to rails for how to achieve this.

One way this might work better too, is to have the "concerns" of app gen be inside lucky/another repo, and have the "lucky cli" functions in this repo, then clone via linked tag/edge from there.

Lots of ways to achieve this easily, but picking the best way for the future is important here.