feat: add create package for simpler project init

[chrispcampbell]

Fixes #228

See issue for more details. This adds a new @sdeverywhere/create package that works in conjunction with npm create so that you can now type:

npm create @sdeverywhere

It walks the user through a series of steps to automate the process of setting up a new project that uses SDEverywhere, so you can go from Vensim mdl to library / app / model-check in a few seconds.

As part of this, there are two new packages, template-default and template-minimal under the examples directory. These are used as templates by the create package. We could possibly add others later to cover different use cases.

Here's a screenshot:

/cc @ToddFincannon

[chrispcampbell]

I'll be merging this as is so that I can publish the initial versions of the create and plugin-config packages and do some testing to make sure they work as intended.