Allow generic type in TypeScript class in no-empty-glimmer-component-classes rule

[chrisrng]

• This fixes the issue brought up here Account for class only having template tag in no-empty-glimmer-component-classes rule #1866 (comment)
• Made updates to initESLint within tests/lib/rules-preprocessor/gjs-gts-processor-test.js to allow for a custom parser so that it can handle .gts files too
• Note if you are only adding a type to the component class not the subclass then you must use templateOnlyComponent from @ember/component/template-only see https://typed-ember.gitbook.io/glint/environments/ember/template-only-components