Upgrade to `babel-plugin-ember-template-compilation` v2

[dfreeman]

The 2.0 release of babel-plugin-ember-template-compilation introduces the ability for template AST transforms to manipulate JS scope, but it also reworked the plugin's options format slightly, so we need to adjust how we configure it here.

Note: this diff is more legible with the "Hide whitespace changes" button, as a fair chunk of change in utils.js is moving logic we no longer need for babel-plugin-ember-template-compilation under the other arm of the surrounding conditional.

I've tested this out in a couple medium-sized projects that are on Ember 3.27+, but I'd love extra 👀 (particularly from @ef4)

[asakusuma]

I tested this change out on a big app and a very big app, no problems

EDIT: both apps are on 3.28