Part of #110497

fixes #106091

modernize vscode.resolveNotebookContentProviders-command, fyi @rebornix didn't find a unit-test for this!

Mark .ember-cli as jsonc instead of json

fixes #109219

fixes #107697

Add a setting to include word based suggestions regardless of the language

Use new completion label for imported modules

The .ember-cli file generated by Ember is JSON with Comments (jsonc): https://github.com/ember-cli/ember-cli/blob/master/blueprints/app/files/.ember-cli

I've changed its associated language accordingly because it being the JSON type by default causes red underlines in the generated file.