Migrate spec/javascripts/groups/ to Jest

Description

Let's migrate the specs in spec/javascripts/groups/ from Karma to Jest.

See the related epic for how to do this.

• spec/javascripts/groups/mock_data.js
• spec/javascripts/groups/components/item_actions_spec.js
• spec/javascripts/groups/components/groups_spec.js
• spec/javascripts/groups/components/item_stats_spec.js
• spec/javascripts/groups/components/app_spec.js
• spec/javascripts/groups/components/item_type_icon_spec.js
• spec/javascripts/groups/components/group_folder_spec.js
• spec/javascripts/groups/components/item_caret_spec.js
• spec/javascripts/groups/components/group_item_spec.js
• spec/javascripts/groups/components/item_stats_value_spec.js
• spec/javascripts/groups/service/groups_service_spec.js
• spec/javascripts/groups/store/groups_store_spec.js