snowpack-start, for easier Snowpack startup

[awu43]

The problem: manually customizing templates from create-snowpack-app was annoying.

The solution: snowpack-start (snowpack-init was already taken). snowpack-start installs your packages and generates boilerplate so you can get to developing faster.

Essentially, it takes the official templates from create-snowpack-app and makes the appropriate changes and additions based on user input. Please try it out and let me know what you think.