feat(admin): add custom admin route ranking feature (#13946)

* ✨ Add custom admin routes ranking

* 🐛 Fix sorting

* 📝 Update admin ui-routes documentation

* ✅ Add admin menu items spec

* 🔧 Add changeset

* 🐛 Remove redundant undefined initializations

* 🔥 🔥 Move the documentation to a separate PR

* ♻️ Move sorting logic to utils

* 🔧 Update changeset

---------

Co-authored-by: Bastien MONTOIS <bqst@bqst-hqckintosh.home>

packages/admin/admin-sdk/src/config/types.ts

@@ -31,6 +31,12 @@ export interface RouteConfig {
    */
   nested?: NestedRoutePosition
 
+  /**
+   * The ranking of the route among sibling routes. Routes are sorted in ascending order (lower rank appears first).
+   * If not provided, the route will be ranked after all routes with explicit ranks.
+   */
+  rank?: number
+
   /**
    * An optional i18n namespace for translating the label. When provided, the label will be treated as a translation key.
    * @example