NX-507: Smoke IT added

Changes:
* added "modern" IT module with one "smoke" testing IT
* added client bits to make possible to create NPM proxy repository via client
* added mock NPM registry. The current mock registry (in smoke IT) works just fine with NPM CLI executing `npm install commonjs`

In short, to have your IT create and start a mock NPM registry, just create a folder called `registry` in `src/test/it-resources` folder in the _same package where your IT is_.

Then lay down the desired files, with metadata files (registry root, package and version) as being named `data.json` in the given directory root (so, in `registry` directory, `registry/package` or `registry/package/version` directories). The `data.json` will be filtered and served to client. Filtering is currently quite basic, only one expression is filtered for: `${npmRegistryUrl}`