Improve get_alerts efficiency

[talboren]

Is your feature request related to a problem? Please describe.
Right now, when requesting alerts from the backend, we get all the alerts a specific tenant has.
get_alerts should return the last instance for every alert, based on fingerprint, and the alerts history only when the history modal is opened.

Describe the solution you'd like
get_alerts to return last instance of a fingerprint
get_alerts_history(fingerprint) to return all the instances of the same alert, paginated