wrong import paths to generated data wrappers on Windows

[vlukashov]

The TS generator on Windows generates incorrect import paths to TS wrappers for data classes.

Example on Windows (incorrect)

// @ts-ignore
import client from './connect-client.default';
import Product from '..\.\com\vaadin\polyglotdx\data\Product';

export function list(): Promise<Array<Product | null> | null> {
  return client.call('ProductEndpoint', 'list', undefined, {requireCredentials: false});
}

Same file generated on Mac OS (correct)

// @ts-ignore
import client from './connect-client.default';
import Product from './com/vaadin/polyglotdx/data/Product';

export function list(): Promise<Array<Product | null> | null> {
  return client.call('ProductEndpoint', 'list', undefined, {requireCredentials: false});
}

Steps to reproduce (on a Windows 10 machine):

• download and extract the attached project polyglot-dx-0.9.2-1c-show-backend-data.zip
• in the project older run npm install && npm start

• see that the build fails with the following error message:

  ERROR in [at-loader] ./frontend/generated/ProductEndpoint.ts:3:21
  TS2307: Cannot find module '...com♂aadinpolyglotdxdataProduct'.
  
  ? Vaadin Connect There are compilation errors in the frontend code

Expected behavior:

• the build passes OK (which is the case on on Mac OS)