Frappe LMS: Quiz result manipulation and cross-user submission forgery

Frappe Learning Management System (LMS) is a learning system that helps users structure their content. Prior to version 2.54.0, quiz submission records are not adequately authorized on the server. Through a `REST` bypass, an authenticated student can record a passing or perfect quiz result without their answers being verified, unlocking course completion and certificates. The student can also create a submission attributed to another user, exhausting that user's allowed attempts and blocking legitimate submissions. These integrity and availability issues are scoped to quiz results; they do not expose other users' data or grant elevated roles. This issue is fixed in version 2.54.0.