[COMMAND MENU ITEMS] Create union type for command menu item payload (#19432)

Replace generic JSON scalar with a typed GraphQL union
CommandMenuItemPayload (PathNavigationPayload |
ObjectMetadataNavigationPayload) for the CommandMenuItem.payload field

packages/twenty-front/src/modules/command-menu-item/graphql/fragments/commandMenuItemFragment.ts

@@ -16,7 +16,14 @@ export const COMMAND_MENU_ITEM_FRAGMENT = gql`
     shortLabel
     position
     isPinned
-    payload
+    payload {
+      ... on PathCommandMenuItemPayload {
+        path
+      }
+      ... on ObjectMetadataCommandMenuItemPayload {
+        objectMetadataItemId
+      }
+    }
     hotKeys
     conditionalAvailabilityExpression
     availabilityType