Lint against .gl- classes in stylesheets

.eslintrc.yml

.stylelintrc

app/assets/stylesheets/bootstrap_migration_components.scss

app/assets/stylesheets/components/action_card_component.scss

app/assets/stylesheets/components/avatar.scss

app/assets/stylesheets/components/content_editor.scss

app/assets/stylesheets/components/ref_selector.scss

app/assets/stylesheets/components/related_items_list.scss

app/assets/stylesheets/components/whats_new.scss

app/assets/stylesheets/mailers/notify.scss

app/assets/stylesheets/mailers/notify_enhanced.scss

app/assets/stylesheets/page_bundles/_pipeline_mixins.scss

app/assets/stylesheets/page_bundles/_system_note_styles.scss

...ts/stylesheets/page_bundles/alert_management_details.scss

app/assets/stylesheets/page_bundles/clusters.scss

app/assets/stylesheets/page_bundles/commits.scss

app/assets/stylesheets/page_bundles/environments.scss

app/assets/stylesheets/page_bundles/ide.scss

app/assets/stylesheets/page_bundles/incidents.scss

app/assets/stylesheets/page_bundles/issuable.scss