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/src/Endpoints/PaymentEndpoint.php

@@ -0,0 +1,152 @@
+<?php
+
+namespace Mollie\Api\Endpoints;
+
+use Mollie\Api\Exceptions\ApiException;
+use Mollie\Api\Resources\Payment;
+use Mollie\Api\Resources\PaymentCollection;
+use Mollie\Api\Resources\Refund;
+use Mollie\Api\Resources\ResourceFactory;
+class PaymentEndpoint extends \Mollie\Api\Endpoints\CollectionEndpointAbstract
+{
+    protected $resourcePath = "payments";
+    /**
+     * @var string
+     */
+    public const RESOURCE_ID_PREFIX = 'tr_';
+    /**
+     * @return Payment
+     */
+    protected function getResourceObject()
+    {
+        return new \Mollie\Api\Resources\Payment($this->client);
+    }
+    /**
+     * Get the collection object that is used by this API endpoint. Every API endpoint uses one type of collection object.
+     *
+     * @param int $count
+     * @param \stdClass $_links
+     *
+     * @return PaymentCollection
+     */
+    protected function getResourceCollectionObject($count, $_links)
+    {
+        return new \Mollie\Api\Resources\PaymentCollection($this->client, $count, $_links);
+    }
+    /**
+     * Creates a payment in Mollie.
+     *
+     * @param array $data An array containing details on the payment.
+     * @param array $filters
+     *
+     * @return Payment
+     * @throws ApiException
+     */
+    public function create(array $data = [], array $filters = [])
+    {
+        return $this->rest_create($data, $filters);
+    }
+    /**
+     * Update the given Payment.
+     *
+     * Will throw a ApiException if the payment id is invalid or the resource cannot be found.
+     *
+     * @param string $paymentId
+     *
+     * @param array $data
+     * @return Payment
+     * @throws ApiException
+     */
+    public function update($paymentId, array $data = [])
+    {
+        if (empty($paymentId) || \strpos($paymentId, self::RESOURCE_ID_PREFIX) !== 0) {
+            throw new \Mollie\Api\Exceptions\ApiException("Invalid payment ID: '{$paymentId}'. A payment ID should start with '" . self::RESOURCE_ID_PREFIX . "'.");
+        }
+        return parent::rest_update($paymentId, $data);
+    }
+    /**
+     * Retrieve a single payment from Mollie.
+     *
+     * Will throw a ApiException if the payment id is invalid or the resource cannot be found.
+     *
+     * @param string $paymentId
+     * @param array $parameters
+     * @return Payment
+     * @throws ApiException
+     */
+    public function get($paymentId, array $parameters = [])
+    {
+        if (empty($paymentId) || \strpos($paymentId, self::RESOURCE_ID_PREFIX) !== 0) {
+            throw new \Mollie\Api\Exceptions\ApiException("Invalid payment ID: '{$paymentId}'. A payment ID should start with '" . self::RESOURCE_ID_PREFIX . "'.");
+        }
+        return parent::rest_read($paymentId, $parameters);
+    }
+    /**
+     * Deletes the given Payment.
+     *
+     * Will throw a ApiException if the payment id is invalid or the resource cannot be found.
+     * Returns with HTTP status No Content (204) if successful.
+     *
+     * @param string $paymentId
+     *
+     * @param array $data
+     * @return Payment
+     * @throws ApiException
+     */
+    public function delete($paymentId, array $data = [])
+    {
+        return $this->rest_delete($paymentId, $data);
+    }
+    /**
+     * Cancel the given Payment. This is just an alias of the 'delete' method.
+     *
+     * Will throw a ApiException if the payment id is invalid or the resource cannot be found.
+     * Returns with HTTP status No Content (204) if successful.
+     *
+     * @param string $paymentId
+     *
+     * @param array $data
+     * @return Payment
+     * @throws ApiException
+     */
+    public function cancel($paymentId, array $data = [])
+    {
+        return $this->rest_delete($paymentId, $data);
+    }
+    /**
+     * Retrieves a collection of Payments from Mollie.
+     *
+     * @param string $from The first payment ID you want to include in your list.
+     * @param int $limit
+     * @param array $parameters
+     *
+     * @return PaymentCollection
+     * @throws ApiException
+     */
+    public function page($from = null, $limit = null, array $parameters = [])
+    {
+        return $this->rest_list($from, $limit, $parameters);
+    }
+    /**
+     * Issue a refund for the given payment.
+     *
+     * The $data parameter may either be an array of endpoint parameters, a float value to
+     * initiate a partial refund, or empty to do a full refund.
+     *
+     * @param Payment $payment
+     * @param array|float|null $data
+     *
+     * @return Refund
+     * @throws ApiException
+     */
+    public function refund(\Mollie\Api\Resources\Payment $payment, $data = [])
+    {
+        $resource = "{$this->getResourcePath()}/" . \urlencode($payment->id) . "/refunds";
+        $body = null;
+        if (($data === null ? 0 : \count($data)) > 0) {
+            $body = \json_encode($data);
+        }
+        $result = $this->client->performHttpCall(self::REST_CREATE, $resource, $body);
+        return \Mollie\Api\Resources\ResourceFactory::createFromApiResult($result, new \Mollie\Api\Resources\Refund($this->client));
+    }
+}