[BUGFIX beta] Partially revert #12229 and add a test for #13432

[Serabe]

This PR partially reverts #12229 given that it made the inline form of
components extending from LinkTo impossible.

Beware that matching the exact behaviour is not there yet (as it wasn't
before #12229) given that {{{link-to title route}}} would unescape title
while {{{my-link-to title route}}} would not. This behaviour was not working
before and therefore is not working after this revert.

This PR does not address whether the inline form for link-to should be
deprecated or not.

[Serabe]

OTOH, I think the behaviour for triple curlies in link-to should be deprecated given:

• It is a hack not easily replicable in the component itself.
• Makes link-to behave differently from other components.
• That behaviour cannot be ported easily to all components extending from link-to.
• It can be easily transformed from {{{link-to title route}}} to {{#link-to route}} {{{title}}} {{/link-to}}.

[rwjblue]

Ultimately, I'd like to deprecate this inline form for custom Ember.LinkComponent classes (and possibly even for all inline link-to), so leaving the AST transform for {{link-to 'thing' 'thing'}} but bringing back support in packages/ember-routing-views/lib/components/link-to.js allows us to support the old behavior and still deprecate custom LinkComponent inline form.

tldr; Leave the AST transform added in #12229 in, add the test you have added here, and revert the changes #12229 made to packages/ember-routing-views/lib/components/link-to.js.

[Serabe]

Updated! Thank you for the quick response!

[rwjblue]

Awesome, this LGTM. We are having an issue with Sauce Labs ATM (they aren't recognizing one of the Firefox builds). I'll try to dig into that later today.

[rwjblue]

#13439 should have fixed the build, thanks for rebasing so quickly

[rwjblue]

Thanks @Serabe!