feat: add glimmer langs

[IgnaceMaes]

Adds support for .gjs and .gts file formats. Glimmer <template> tag components are the new format which power Ember.js. References:

• RFC: https://rfcs.emberjs.com/id/0779-first-class-component-templates
• Component implementation: https://github.com/ember-template-imports/ember-template-imports

Local tests

Classes

Style tag

[thecrypticace]

Thanks — tested this and it works as expected! Appreciate it.

This should be in the pre-release extension soon-ish (~10 minutes I think?)