cart & checkout: apply validation based on required inputs in each service & add phone input in checkout page

src/assets/locals/en.json

@@ -231,7 +231,8 @@
     "plateNumber": "Plate Number",
     "plateNumberPlaceholder": "Enter plate number",
     "editNote": "Edit Note",
-    "selectTimeEstimate": "Select Estimate Time"
+    "selectTimeEstimate": "Select Estimate Time",
+      "pleaseAddItemsToCart": "Please add items to your cart"
   },
   "checkout": {
     "title": "Checkout",
@@ -248,7 +249,8 @@
     "totalAmount": "Total Amount",
     "items": "Items",
     "expiresIn": "Expires in",
-    "expiresInDescription": "Expires in:12/26"
+    "expiresInDescription": "Expires in:12/26",
+    "phoneNumber": "Phone Number"
   },
   "address": {
     "title": "Address",