Idea for a new rule: No target="_blank" for LinkTo

[amk221]

Here is the scenario I'd like to guard against...

1. User visits a page and enters some form information
2. Users clicks a LinkTo to read Terms and Conditions (with target="_blank")
3. Browser blocks popup
   (it offers the user to "Allow anyway", but is sometimes missed by users because it's small and in the address bar)
4. The Ember router continues to the link destination in the user's main tab.
5. The user presses back
6. The user has lost their form details

This is solved by switching to a hyperlink instead of a LinkTo

Before

<LinkTo @route="terms-and-conditions" target="_blank">
  Terms and Conditions
</Linkto>

After

<a href={{url-for "terms-and-conditions"}} target="_blank">
  Terms and Conditions
</a>

Along with

class UrlForHelper extends Helper {
  @service router;

  compute(args) {
    return this.router.urlFor(...args);
  }
}