Add support for generating a signed URL for downloading a file from the daemon

app/Http/Requests/Api/Client/Servers/Backups/DownloadBackupRequest.php

@@ -0,0 +1,41 @@
+<?php
+
+namespace Pterodactyl\Http\Requests\Api\Client\Servers\Backups;
+
+use Pterodactyl\Models\Backup;
+use Pterodactyl\Models\Server;
+use Pterodactyl\Models\Permission;
+use Pterodactyl\Http\Requests\Api\Client\ClientApiRequest;
+
+class DownloadBackupRequest extends ClientApiRequest
+{
+    /**
+     * @return string
+     */
+    public function permission()
+    {
+        return Permission::ACTION_BACKUP_DOWNLOAD;
+    }
+
+    /**
+     * Ensure that this backup belongs to the server that is also present in the
+     * request.
+     *
+     * @return bool
+     */
+    public function resourceExists(): bool
+    {
+        /** @var \Pterodactyl\Models\Server|mixed $server */
+        $server = $this->route()->parameter('server');
+        /** @var \Pterodactyl\Models\Backup|mixed $backup */
+        $backup = $this->route()->parameter('backup');
+
+        if ($server instanceof Server && $backup instanceof Backup) {
+            if ($server->exists && $backup->exists && $server->id === $backup->server_id) {
+                return true;
+            }
+        }
+
+        return false;
+    }
+}