feat(dashboard): ability to locate new admin route under existing route (#10587)

This PR add ability to locate new admin route under existing route in sidebar.

For example, new route Brands
![image](https://github.com/user-attachments/assets/1b297fb0-296c-4e94-a4cb-f84f4c676c53)
![image](https://github.com/user-attachments/assets/80336909-1c0a-49c9-b8e1-3b1137ae2e48)

https://github.com/user-attachments/assets/b46b1813-e92e-4b67-84a1-84660023ac7c

packages/admin/admin-shared/src/extensions/routes/constants.ts

@@ -0,0 +1,8 @@
+export const NESTED_ROUTE_POSITIONS = [
+  "/orders",
+  "/products",
+  "/inventory",
+  "/customers",
+  "/promotions",
+  "/price-lists",
+] as const

packages/admin/admin-shared/src/extensions/routes/index.ts

@@ -0,0 +1,2 @@
+export * from "./constants"
+export * from "./types"

packages/admin/admin-shared/src/extensions/routes/types.ts

@@ -0,0 +1,3 @@
+import { NESTED_ROUTE_POSITIONS } from "./constants"
+
+export type NestedRoutePosition = (typeof NESTED_ROUTE_POSITIONS)[number]

packages/admin/admin-shared/src/index.ts

@@ -1,3 +1,4 @@
 export * from "./extensions/custom-fields"
+export * from "./extensions/routes"
 export * from "./extensions/widgets"
 export * from "./virtual-modules"