Create fake for npm, which is required to test the tsci init

[imrishabh18]

The packages @tscircuit/core are downloaded on initialisation @types/react

[seveibar]

haha this is a good idea- i like it a lot!!!

I think we would want to have these dependencies "preloaded" into the fake. Because of how simple the npm registry is, this fake is almost just a file server.

An alternative approach to "preloading" is to have the fake look at the local node_modules in order to serve the packages. This is more complex but removes the preloading process