fix #5660 standardized relation icon (#6504)

fix #5660 

- updated One to many [1:N] icon across app
- created many to one icon [N:1] , and added it in app


![download
(2)](https://github.com/user-attachments/assets/35ce05be-0f5f-4cd0-a1b7-7ab9062f74a0)
![download
(1)](https://github.com/user-attachments/assets/57316e49-c931-4ab5-ad4b-d04b241724c3)

---------

Co-authored-by: Félix Malfait <felix.malfait@gmail.com>

packages/twenty-front/src/modules/settings/data-model/constants/RelationTypes.ts

@@ -1,6 +1,7 @@
 import {
   IconComponent,
-  IconLayersLinked,
+  IconRelationManyToOne,
+  IconRelationOneToMany,
   IconRelationOneToOne,
 } from 'twenty-ui';
 
@@ -21,7 +22,7 @@ export const RELATION_TYPES: Record<
 > = {
   [RelationMetadataType.OneToMany]: {
     label: 'Has many',
-    Icon: IconLayersLinked,
+    Icon: IconRelationOneToMany,
     imageSrc: OneToManySvg,
   },
   [RelationMetadataType.OneToOne]: {
@@ -31,7 +32,7 @@ export const RELATION_TYPES: Record<
   },
   MANY_TO_ONE: {
     label: 'Belongs to one',
-    Icon: IconLayersLinked,
+    Icon: IconRelationManyToOne,
     imageSrc: OneToManySvg,
     isImageFlipped: true,
   },