in agent rdv wizard, when duplicate user found, let agent pick it instead of exiting the flow

Created by: adipasquale

https://trello.com/c/KtgcJanE/1019-agent-au-moment-de-la-d%C3%A9tection-dun-usager-d%C3%A9j%C3%A0-existant-dans-le-flow-de-pose-de-rdv-changer-le-bouton-modifier-cet-usager-par-c