Fix User ... lacks permission to update

Correction de l'erreur qui était affichée chez les joueurs lors de
hooks utilisés pour effectuer des modifications sur des
documents:

- ChatMessage, ajout de flags pour l'heure
- Item au sein d'un Actor pour mettre à jour certains éléments

module/misc.js

@@ -166,15 +166,39 @@ export class Misc {
   }
 
   static firstConnectedGM() {
-    return game.users.filter(u => u.isGM && u.active).sort(Misc.ascending(u => u.id)).find(u => u.isGM && u.active);
+    return game.users.sort(Misc.ascending(u => u.id)).find(u => u.isGM && u.active);
+  }
+  static connectedGMs() {
+    return game.users.filter(u => u.isGM && u.active);
   }
 
-  static isOwnerPlayer(actor, user = undefined) {
-    return actor.testUserPermission(user ?? game.user, CONST.DOCUMENT_PERMISSION_LEVELS.OWNER)
+  /**
+   * This helper method allows to get the docuument, for a single user (either first connected GM, or the owner
+   * if there is no connected GMs), or else return undefined.
+   * 
+   * This allows for example update hooks that should apply modifications to actors to be called only for one
+   * user (preventing the "User ... lacks permission to update Item" that was occuring on hooks when Item updates
+   * were triggering other changes)
+   * 
+   * @param {*} document the Document with is potentially an Actor
+   * @returns the actor if either the game.user is the first connected GM, or if the game.user is the owner
+   *  and there is no connected GM
+   */
+  static documentIfResponsible(document) {
+    if (document instanceof Document) {
+      if (Misc.isUniqueConnectedGM() || (Misc.connectedGMs().length == 0 && Misc.isOwnerPlayer(document))) {
+        return document
+      }
+    }
+    return undefined
   }
 
-  static isOwnerPlayerOrUniqueConnectedGM(actor, user = undefined) {
-    return Misc.isOwnerPlayer(actor, user) ?? Misc.isUniqueConnectedGM();
+  static isOwnerPlayer(actor) {
+    return actor.testUserPermission(game.user, CONST.DOCUMENT_PERMISSION_LEVELS.OWNER)
+  }
+
+  static isOwnerPlayerOrUniqueConnectedGM(actor) {
+    return Misc.isOwnerPlayer(actor) ?? Misc.isUniqueConnectedGM();
   }
 
   /**