In the past, the result of template compilation would be stored directly in `Ember.TEMPLATES`. Following the move to more modern ember-cli-based compilation, templates are now compiled to es6 modules. To handle forward/backwards compatibility during these changes we had logic in `discourse-boot` which would extract templates from the es6 modules and store them into the legacy-style `Ember.TEMPLATES` object.
This commit removes that shim, and updates our resolver to fetch templates directly from es6 modules. This is closer to how 'vanilla' Ember handles template resolution. We still have a lot of discourse-specific logic, but now it is centralised in one location and should be easier to understand and normalize in future.
This commit should not introduce any behaviour change.
David Taylor