doc(testing): add section on ignoring dependencies

[RomkeVdMeulen]

This describes a new feature of aurelia-testing introduced by aurelia/testing#89

[RomkeVdMeulen]

The section isn't very extensive, but the API is pretty straight-forward anyway. I tried to match the tone of the rest of the article.

The PR to aurelia-testing already includes a test that pretty much matches the code sample I added here. But to be complete, something like this might be added to to doc-samples.spec.ts as well:

describe('MyParentComponent', () => {

  it('doesn\'t load the subcomponent', async () => {
    const component = StageComponent
      .withResources('test/resources/my-parent-component')
      .inView('<my-parent-component></my-parent-component>')
      .ignoreDependencies('test/resources/my-component');
    await component.create(bootstrap);
    expect(component.element.textContent!.trim()).toEqual('');
  });
});

[bigopon]

This is nice. I think we may want to emphasize how url will be matched though: loader will resolve dependencies to their absolute url, based on its base url. So if the router base url is at '.' and you want ignore something at src/something, it should be done by:

ignoreDependencies('src/something');

[RomkeVdMeulen]

Something like that?

[RomkeVdMeulen]

@EisenbergEffect The feature being described here isn't finished yet. I'm not sure this change should be going live yet.

[bigopon]

Yes, there are subtle differences between webpack-loader / default-loader that I haven't been able to address. I've put it on hold so far. Default loader seems to be harder to debug than I imagined

[EisenbergEffect]

Apologies! I've reverted the documentation so it doesn't go out on Monday.
Sorry for the hassle, but when it's ready can you submit a new PR? Thank you.