Fix translation keys and participant pluralization in list_with_period.html.twig

Updated French translations for "Participants" and improved pluralization handling in accompanying_period keys. Modified list_with_period.html.twig to dynamically translate "Participants" based on the count of current participations.

src/Bundle/ChillPersonBundle/Resources/views/Person/list_with_period.html.twig

@@ -100,7 +100,7 @@
                     <div class="wl-row">
                         <div class="wl-col title">
                             <h3 class="participants">
-                                {{ 'Participants'|trans }}
+                                {{ 'accompanying_period.Participants_without_count'|trans({count: acp.currentParticipations|length}) }}
                             </h3>
                         </div>
                         <div class="wl-col list">

src/Bundle/ChillPersonBundle/translations/messages+intl-icu.fr.yaml

@@ -13,6 +13,14 @@ Requestor: >-
         neutral {Demandeur·euse}
     }
 
+accompanying_period:
+    Participants_without_count: >-
+        {count, plural,
+            =0 {Participant}
+            =1 {Participant}
+            other {Participants}
+        }
+
 person:
     from_the: depuis le
     And himself: >-

src/Bundle/ChillPersonBundle/translations/messages.fr.yml

@@ -208,7 +208,7 @@ Pediod closing form is not valid: Le formulaire n'est pas valide
 Accompanying user: Accompagnant
 No accompanying user: Aucun accompagnant
 No data given: Pas d'information
-Participants: Usagers impliquées
+Participants: Usagers impliqués
 Create an accompanying course: Créer un parcours
 Accompanying courses of users: Parcours des utilisateurs
 This accompanying course is still a draft: Ce parcours est encore à l'état brouillon.