linting

src/app/group-monitor/backend.service.ts

src/app/group-monitor/booklet.service.spec.ts

src/app/group-monitor/group-monitor-routing.module.ts

src/app/group-monitor/group-monitor.component.html

src/app/group-monitor/group-monitor.component.ts

src/app/group-monitor/group-monitor.interfaces.ts

src/app/group-monitor/group-monitor.module.ts

src/app/group-monitor/test-view/test-view.component.spec.ts

src/app/group-monitor/test-view/test-view.component.ts

src/app/group-monitor/websocket-backend.service.ts

src/app/group-monitor/websocket.service.ts