Add support for .gjs/.gts

[dknutsen]

If you want an unsupported language added, provide:

• language name: "Glimmer JavaScript" and "Glimmer TypeScript"
• file extension(s): .gjs and .gts
• method(s) of commenting text: handlebars comments {{! ... }} {{!-- ... --}} <!-- ... --> and js/ts comments // ... /* ... */
• location of sample code: https://github.com/miguelcobain/ember-yeti-table/blob/a6642a4f16b6786a0f72d1caaa3270d0cb194d05/ember-yeti-table/src/components/yeti-table/body.gjs https://github.com/josemarluedke/frontile/blob/a9680f2681a8b1193feba0fdc27871566bcde120/packages/forms/src/components/input.gts

This represents the new component authoring format for Ember.js. It is essentially javascript/typescript with embedded handlebars templates, so comment format includes javascript style comments as well as html and handlebars format comments