Missing Context and Capability Validation in External Service

[volodymyrdovhan]

Hello,

I found an issue with missing capabilities and context validation in the external services.

Please review the documentation for more details:
Context and Capability Checks - Moodle External Services

Please add security checks based on the requirements:

// Perform security checks.
$context = context_course::instance($courseid);
self::validate_context($context);
require_capability(CAPABILITY_NAME, $context);