feat(customer_v2): add route for customer retrieve v2 (#5516)

Co-authored-by: Narayan Bhat <narayan.bhat@juspay.in>
Co-authored-by: hrithikesh026 <hrithikesh.vm@juspay.in>
Co-authored-by: Prajjwal Kumar <prajjwal.kumar@juspay.in>
Co-authored-by: Sanchith Hegde <sanchith.hegde@juspay.in>
Co-authored-by: hyperswitch-bot[bot] <148525504+hyperswitch-bot[bot]@users.noreply.github.com>
Co-authored-by: Sahkal Poddar <sahkalpoddar@Sahkals-MacBook-Air.local>

api-reference-v2/openapi_spec.json

@@ -4954,7 +4954,8 @@
         "type": "object",
         "required": [
           "merchant_reference_id",
-          "created_at"
+          "created_at",
+          "id"
         ],
         "properties": {
           "merchant_reference_id": {
@@ -5032,6 +5033,10 @@
             "example": "pm_djh2837dwduh890123",
             "nullable": true,
             "maxLength": 64
+          },
+          "id": {
+            "type": "string",
+            "description": "Global id"
           }
         }
       },