[#108] Required notification's content and fix snackbar
Added also a better text for the notification's snackbar
Backend MR: https://gitlab.cern.ch/push-notifications/backend/-/merge_requests/95
Edited by Caetan Tojeiro Carpente
Added also a better text for the notification's snackbar
Backend MR: https://gitlab.cern.ch/push-notifications/backend/-/merge_requests/95