Refactor authorization and token refresh logic; update tax handling and invoice generation

- Changed variable name from `$stmt_service` to `$stmt_refreshkey` for clarity in `authorization.php` and `token_refresh.php`.
- Added null coalescing operator to ensure criteria are set to an empty string if not provided in `products_software_versions.php`.
- Modified SQL script to add `eu` column to `taxes` table and update tax rates based on EU membership.
- Enhanced invoice generation logic in `functions.php` to include VAT notes based on customer country and VAT number.
- Updated email and PDF templates to display VAT notes and percentages correctly.
- Adjusted JavaScript tax calculation logic to handle VAT based on country and VAT number.
- Fixed API URL in `index.php` for token refresh endpoint.
- Updated countries data structure in `countries.php` to include EU membership status.

index.php

@@ -54,7 +54,7 @@ if (!isset($_SESSION['authorization']['userkey']) ||
 
     // Token missing, expired, or about to expire - get new token
     if (isset($_SESSION['authorization']['refreshkey'])) {
-        $api_url = '/v2/token_refresh?refreshkey='.$_SESSION['authorization']['refreshkey'];
+        $api_url = '/v2/token_refresh/refreshkey='.$_SESSION['authorization']['refreshkey'];
         $responses = ioServer($api_url, '');
 
         //Decode Payload