[REGRESSION] Omnichannel visitor forward was applying wrong restrictions (#17826)

* return empty object if there is no callback

* Improve department forward restrictions

app/livechat/server/methods/getDepartmentForwardRestrictions.js

@@ -8,6 +8,9 @@ Meteor.methods({
 			throw new Meteor.Error('error-invalid-user', 'Invalid user', { method: 'livechat:getDepartmentForwardRestrictions' });
 		}
 
-		return callbacks.run('livechat.onLoadForwardDepartmentRestrictions', departmentId);
+		const options = callbacks.run('livechat.onLoadForwardDepartmentRestrictions', { departmentId });
+		const { restrictions } = options;
+
+		return restrictions;
 	},
 });

ee/app/livechat-enterprise/server/hooks/onLoadForwardDepartmentRestrictions.js

@@ -1,17 +1,18 @@
 import { callbacks } from '../../../../../app/callbacks';
 import { LivechatDepartment } from '../../../../../app/models/server';
 
-callbacks.add('livechat.onLoadForwardDepartmentRestrictions', (departmentId) => {
+callbacks.add('livechat.onLoadForwardDepartmentRestrictions', (options = {}) => {
+	const { departmentId } = options;
 	if (!departmentId) {
-		return {};
+		return options;
 	}
 	const department = LivechatDepartment.findOneById(departmentId, { fields: { departmentsAllowedToForward: 1 } });
 	if (!department) {
-		return {};
+		return options;
 	}
 	const { departmentsAllowedToForward } = department;
 	if (!departmentsAllowedToForward) {
-		return {};
+		return options;
 	}
-	return { _id: { $in: departmentsAllowedToForward } };
+	return Object.assign({ restrictions: { _id: { $in: departmentsAllowedToForward } } }, options);
 }, callbacks.priority.MEDIUM, 'livechat-on-load-forward-department-restrictions');