fix(dashboard,medusa): Fixes to Customer and Customer Groups domains (#7081)

**What**
- Cleanup of domains
- Adds toasts
- Adds delete customer hook
- Fixes validation of create and update customer endpoints.

packages/admin-next/dashboard/src/hooks/api/customers.tsx

@@ -1,3 +1,8 @@
+import {
+  AdminCustomerListResponse,
+  AdminCustomerResponse,
+  DeleteResponse,
+} from "@medusajs/types"
 import {
   QueryKey,
   UseMutationOptions,
@@ -9,10 +14,6 @@ import { client } from "../../lib/client"
 import { queryClient } from "../../lib/medusa"
 import { queryKeysFactory } from "../../lib/query-key-factory"
 import { CreateCustomerReq, UpdateCustomerReq } from "../../types/api-payloads"
-import {
-  AdminCustomerResponse,
-  AdminCustomerListResponse,
-} from "@medusajs/types"
 
 const CUSTOMERS_QUERY_KEY = "customers" as const
 export const customersQueryKeys = queryKeysFactory(CUSTOMERS_QUERY_KEY)
@@ -88,3 +89,21 @@ export const useUpdateCustomer = (
     ...options,
   })
 }
+
+export const useDeleteCustomer = (
+  id: string,
+  options?: UseMutationOptions<DeleteResponse, Error, void>
+) => {
+  return useMutation({
+    mutationFn: () => client.customers.delete(id),
+    onSuccess: (data, variables, context) => {
+      queryClient.invalidateQueries({ queryKey: customersQueryKeys.lists() })
+      queryClient.invalidateQueries({
+        queryKey: customersQueryKeys.detail(id),
+      })
+
+      options?.onSuccess?.(data, variables, context)
+    },
+    ...options,
+  })
+}