show group(s) on group-monitor entry screen

...p/app-root/monitor-starter/monitor-starter.component.html

...app/app-root/monitor-starter/monitor-starter.component.ts

src/app/app.interfaces.ts

src/app/backend.service.ts

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

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

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