AI availability

Quiz access plugin that prevents students from entering a quiz with questions that require the access to AI functionalities.
General functionality:
This quiz accessrule plugin prevents users from starting or continuing quiz attempts if the AI functionalities required by questions with certain question types are not available or permitted for them.
Features:
Detects AI-dependent quizzes (currently those containing qtype_aitext questions) and blocks access if AI is unavailable through local_ai_manager.
Respects AI availability and any course-level controls exposed by the local_ai_manager backend.
Provides meaningful error messages when AI is disabled, misconfigured, or required purposes (e.g. feedback/translate) are not allowed.
Plays nicely with Moodle’s quiz access rules: only activates when AI is needed; otherwise stays out of the way.