[chore:] implemented GetCustomerByID()

DataStore/Settings.cs

@@ -165,6 +165,19 @@ public class Customer
     public char separator { get; set; } = ',';
     public int ID { get; }
 
+    public static Customer GetCustomerByID(int id)
+    {
+        foreach (var customer in Settings._instance.customers.customers)
+        {
+            if (id == customer.ID)
+            {
+                return customer;
+            }
+        }
+
+        return null;
+    }
+
 
     // public static int GetIDByCustomerListItem(string item_content)
     // {