Add Mollie API integration and webhook for software upgrade payments

- Introduced the `CaBundle.php` class for managing CA certificates.
- Updated `installed.json` and `installed.php` to include the new `composer/ca-bundle` dependency.
- Added `platform_check.php` to enforce PHP version requirements.
- Created `initialize.php` for initializing the Mollie API client with the API key.
- Implemented `webhook_mollie.php` to handle webhook callbacks for software upgrade payments, including transaction status updates and invoice generation.
- Integrated DomPDF for generating invoices and sending them via email.

assets/mollie/vendor/autoload.php

@@ -0,0 +1,31 @@
+<?php
+
+// scoper-composer-autoload.php @generated by PhpScoper
+
+$loader = require_once __DIR__.'/composer-autoload.php';
+
+// Aliases for the whitelisted classes. For more information see:
+// https://github.com/humbug/php-scoper/blob/master/README.md#class-whitelisting
+if (!class_exists('ComposerAutoloaderInit617dbc66d182e97844e7363117763c69', false) && !interface_exists('ComposerAutoloaderInit617dbc66d182e97844e7363117763c69', false) && !trait_exists('ComposerAutoloaderInit617dbc66d182e97844e7363117763c69', false)) {
+    spl_autoload_call('_PhpScoperf7c63b60b99d\ComposerAutoloaderInit617dbc66d182e97844e7363117763c69');
+}
+
+// Functions whitelisting. For more information see:
+// https://github.com/humbug/php-scoper/blob/master/README.md#functions-whitelisting
+if (!function_exists('database_write')) {
+    function database_write() {
+        return \_PhpScoperf7c63b60b99d\database_write(...func_get_args());
+    }
+}
+if (!function_exists('database_read')) {
+    function database_read() {
+        return \_PhpScoperf7c63b60b99d\database_read(...func_get_args());
+    }
+}
+if (!function_exists('printOrders')) {
+    function printOrders() {
+        return \_PhpScoperf7c63b60b99d\printOrders(...func_get_args());
+    }
+}
+
+return $loader;