[lenaherf]

Note: Please fill out all relevant sections and remove irrelevant ones.

🔀 Purpose of this PR:

• Fixes a bug
• Updates for a new Moodle version
• Adds a new feature of functionality
• Improves or enhances existing features
• Refactoring: restructures code for better performance or maintainability
• Testing: add missing or improve existing tests
• Miscellaneous: code cleaning (without functional changes), documentation, configuration, ...

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📝 Description:

This PR adds optional creation and synchronization of Moodle course groups based on individual student bookings in Scheduler group slots.
Three configuration modes are available:

• Do not create course groups.
• Create a course group when a group slot is created.
• Create a course group when the first individual booking is made for a group slot.
  Each generated course group is associated with its corresponding Scheduler slot. When an individual booking is added or cancelled, the student is added to or removed from the associated course group accordingly.
  Group bookings are not synchronized, because their membership is already represented by the existing Moodle group used for the booking.
  Synchronization continues only while the Scheduler slot exists. Deleting a slot does not delete its generated course group. The group remains in the course with its membership at the time of deletion. This avoids deleting course groups or membership data that may already be used elsewhere.

📋 Checklist

Please confirm the following (check all that apply):

• I have phpunit and/or behat tests that cover my changes or additions.
• Code passes the code checker without errors and warnings.
• Code passes the moodle-ci/cd pipeline on all supported Moodle versions or the ones the plugin supports.
• Code does not have var_dump() or var_export or any other debugging statements (or commented out code) that
  should not appear on the productive branch.
• Code only uses language strings instead of hard-coded strings.
• If there are changes in the database: I updated/created the necessary upgrade steps in db/upgrade.php and
  updated the version.php.
• If there are changes in javascript: I build new .min files with the grunt amd command.
• If it is a Moodle update PR: I read the release notes, updated the version.php and the CHANGES.md.
  I ran all tests thoroughly checking for errors. I checked if bootstrap had any changes/deprecations that require
  changes in the plugins UI.

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🔍 Related Issues

• Related to Generate Moodle Course Groups from Slots #92

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🧾📸🌐 Additional Information (like screenshots, documentation, links, etc.)

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