npm package name validation

[granicz]

When using npm package-based imports, such as:

let QRCode = JS.Import("foo", "date-fns")

then raise an error, if the given npm package is not defined in the project file, say, using the femto convention:

<NpmDependencies>
    <NpmPackage Name="date-fns" Version="gt 1.30.0 lt 2.0.0" ResolutionStrategy="Max" />
</NpmDependencies>

[Jand42]

@granicz First I am adding the possibility npm package-based imports.

I am modifying JS.Import to follow rules used by JS imports too:

• if you want to import a locally defined module (resource in current assembly), you can do that as JS.Import("foo", "./localEmbedded.js").
• Similartly, importing from another WS assembly should look like a relative path JS.Import("foo", "../AnotherLib/embedded.js")
• Finally, as you write JS.Import("foo", "date-fns") will import from npm package "date-fns". Generally, if the import path does not start with ./ or ../, it is preserved exactly.