fix: lazy-ngmodule-hot-loader breaks the sourceMaps

[rosen-vladimirov]

The lazy-ngmodule-hot-loader breaks sourceMaps as it does not pass them to the next loaders. This breaks debugging with --bundle in VSCode extension as the files included in the sourcesContent cannot be mapped correctly to local files.

PR Checklist

• The PR title follows our guidelines: https://github.com/NativeScript/NativeScript/blob/master/CONTRIBUTING.md#commit-messages.
• There is an issue for the bug/feature this PR is for. To avoid wasting your time, it's best to open a suggestion issue first and wait for approval before working on it.
• You have signed the CLA.
• All existing tests are passing: https://github.com/NativeScript/nativescript-dev-webpack/blob/master/CONTRIBUTING.md#testing-locally-by-running-e2e-tests
• Tests for the changes are included.

What is the current behavior?

• Unable to debug Angular projects in VSCode.
• When debugging Angular projects in Chrome DevTools, the content of the files under webpack is not the same as your actual content - it's not TypeScript anymore:
  

What is the new behavior?

• You can debug Angular projects in VSCode
• Sources under webpack in Chrome DevTools are correct

Fixes nativescript-community/nativescript-vscode-extension#232

[sis0k0]

Good catch! @dtopuzov, @rosen-vladimirov , is there a way to execute tests for debugging on PR of the webpack plugin?