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/EndpointAbstract.php

@@ -0,0 +1,163 @@
+<?php
+
+namespace Mollie\Api\Endpoints;
+
+use Mollie\Api\Exceptions\ApiException;
+use Mollie\Api\MollieApiClient;
+use Mollie\Api\Resources\BaseResource;
+use Mollie\Api\Resources\ResourceFactory;
+abstract class EndpointAbstract
+{
+    public const REST_CREATE = \Mollie\Api\MollieApiClient::HTTP_POST;
+    public const REST_UPDATE = \Mollie\Api\MollieApiClient::HTTP_PATCH;
+    public const REST_READ = \Mollie\Api\MollieApiClient::HTTP_GET;
+    public const REST_LIST = \Mollie\Api\MollieApiClient::HTTP_GET;
+    public const REST_DELETE = \Mollie\Api\MollieApiClient::HTTP_DELETE;
+    /**
+     * @var MollieApiClient
+     */
+    protected $client;
+    /**
+     * @var string
+     */
+    protected $resourcePath;
+    /**
+     * @var string|null
+     */
+    protected $parentId;
+    /**
+     * @param MollieApiClient $api
+     */
+    public function __construct(\Mollie\Api\MollieApiClient $api)
+    {
+        $this->client = $api;
+    }
+    /**
+     * @param array $filters
+     * @return string
+     */
+    protected function buildQueryString(array $filters)
+    {
+        if (empty($filters)) {
+            return "";
+        }
+        foreach ($filters as $key => $value) {
+            if ($value === \true) {
+                $filters[$key] = "true";
+            }
+            if ($value === \false) {
+                $filters[$key] = "false";
+            }
+        }
+        return "?" . \http_build_query($filters, "", "&");
+    }
+    /**
+     * @param array $body
+     * @param array $filters
+     * @return mixed
+     * @throws ApiException
+     */
+    protected function rest_create(array $body, array $filters)
+    {
+        $result = $this->client->performHttpCall(self::REST_CREATE, $this->getResourcePath() . $this->buildQueryString($filters), $this->parseRequestBody($body));
+        return \Mollie\Api\Resources\ResourceFactory::createFromApiResult($result, $this->getResourceObject());
+    }
+    /**
+     * Sends a PATCH request to a single Mollie API object.
+     *
+     * @param string $id
+     * @param array $body
+     *
+     * @return mixed
+     * @throws ApiException
+     */
+    protected function rest_update($id, array $body = [])
+    {
+        if (empty($id)) {
+            throw new \Mollie\Api\Exceptions\ApiException("Invalid resource id.");
+        }
+        $id = \urlencode($id);
+        $result = $this->client->performHttpCall(self::REST_UPDATE, "{$this->getResourcePath()}/{$id}", $this->parseRequestBody($body));
+        if ($result == null) {
+            return null;
+        }
+        return \Mollie\Api\Resources\ResourceFactory::createFromApiResult($result, $this->getResourceObject());
+    }
+    /**
+     * Retrieves a single object from the REST API.
+     *
+     * @param string $id Id of the object to retrieve.
+     * @param array $filters
+     * @return mixed
+     * @throws ApiException
+     */
+    protected function rest_read($id, array $filters)
+    {
+        if (empty($id)) {
+            throw new \Mollie\Api\Exceptions\ApiException("Invalid resource id.");
+        }
+        $id = \urlencode($id);
+        $result = $this->client->performHttpCall(self::REST_READ, "{$this->getResourcePath()}/{$id}" . $this->buildQueryString($filters));
+        return \Mollie\Api\Resources\ResourceFactory::createFromApiResult($result, $this->getResourceObject());
+    }
+    /**
+     * Sends a DELETE request to a single Molle API object.
+     *
+     * @param string $id
+     * @param array $body
+     *
+     * @return mixed
+     * @throws ApiException
+     */
+    protected function rest_delete($id, array $body = [])
+    {
+        if (empty($id)) {
+            throw new \Mollie\Api\Exceptions\ApiException("Invalid resource id.");
+        }
+        $id = \urlencode($id);
+        $result = $this->client->performHttpCall(self::REST_DELETE, "{$this->getResourcePath()}/{$id}", $this->parseRequestBody($body));
+        if ($result == null) {
+            return null;
+        }
+        return \Mollie\Api\Resources\ResourceFactory::createFromApiResult($result, $this->getResourceObject());
+    }
+    /**
+     * Get the object that is used by this API endpoint. Every API endpoint uses one type of object.
+     *
+     * @return BaseResource
+     */
+    protected abstract function getResourceObject();
+    /**
+     * @param string $resourcePath
+     */
+    public function setResourcePath($resourcePath)
+    {
+        $this->resourcePath = \strtolower($resourcePath);
+    }
+    /**
+     * @return string
+     * @throws ApiException
+     */
+    public function getResourcePath()
+    {
+        if (\strpos($this->resourcePath, "_") !== \false) {
+            [$parentResource, $childResource] = \explode("_", $this->resourcePath, 2);
+            if (empty($this->parentId)) {
+                throw new \Mollie\Api\Exceptions\ApiException("Subresource '{$this->resourcePath}' used without parent '{$parentResource}' ID.");
+            }
+            return "{$parentResource}/{$this->parentId}/{$childResource}";
+        }
+        return $this->resourcePath;
+    }
+    /**
+     * @param array $body
+     * @return null|string
+     */
+    protected function parseRequestBody(array $body)
+    {
+        if (empty($body)) {
+            return null;
+        }
+        return @\json_encode($body);
+    }
+}