Add support for Glimmer JS/TS

[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

[XAMPPRocky]

Thank you for your PR! However it seems like there are CI failures, can you rebase and check them?

[IgnaceMaes]

Thank you for your PR! However it seems like there are CI failures, can you rebase and check them?

Looks like it didn't appreciate a dash within the test filename. Changed to underscores and that seems better 😄

[XAMPPRocky]

Thank you for your PR, and congrats on your first contribution! 🎉