The "New" command should be moved to its own package #244
Description
Many of Emigrate's current dependencies are only used by the "New" command and it's only used in a development environment.
The "New" command should therefore be moved to a separate package so it can be moved to "devDependencies" in each project using Emigrate. This will reduce Emigrate's footprint in production.
By moving the command to a @emigrate/create package a developer would be able to create new migrations using either of:
npm init @emigrate
# or
npx @emigrate/create