rename book_id in po table to booking_id to perform ORM relantionship

added relationship between booking and po
updated settings shows for different role
added function to display po for admin

app/PurchaseOrder.php

@@ -7,4 +7,9 @@ use Illuminate\Database\Eloquent\Model;
 class PurchaseOrder extends Model
 {
     protected $fillable = ['image_url','amount','booking_id'];
+    
+    public function booking()
+    {
+        return $this->belongsTo(Booking::class);
+    }
 }