Reference dotnet-js-interop by source

[pranavkm]

Now that Microsoft.InteropJS is in aspnetcore@master, Web.JS should reference it by source rather than attempting to use the package from the MyGet feed: https://github.com/dotnet/aspnetcore/blob/master/src/Components/Web.JS/package.json#L19

[JunTaoLuo]

FYI, the migration of the package is described in #19254

[pranavkm]

Moving this out to the next sprint (after wasm is merged upstream).