TypeScript: Aliased exports should include aliased name

[devversion]

Let's consider this example:

  export {ObserveContent} from './X';

  /** @deprecated */
  export {ObserveContent as CdkObserveContent} from './X';

This is a common pattern inside of Angular Material, but causes Dgeni to generate documents for both exports.

The second document is identical to the original Dgeni document and doesn't even show the aliased name. It would be useful to have a property that indicates that the given doc is an alias and maybe also refer to the original document.

This issue is mostly for tracking inside of Angular Material (already mentioned on Slack).

[petebacondarwin]

Yes, we need to fix this. I will try to spend some time on it later this week (or early next week).

[petebacondarwin]

See #253

[petebacondarwin]

See #253