Admin settings to control Matrix room creation for Courses

Admins need to be able to control the behaviour of hour Matrix rooms are created for their Moodle instance.

This means controlling the defaults for Matrix room creation at course level in the course settings.

The below user stories outline the functionality.

User stories:

1. As an admin I expect that Matrix chat rooms for existing courses are not enabled by default when I upgrade to Moodle 4.2. So not to confuse the teachers at my organisation.
2. As an admin I expect that Matrix chat rooms for new courses are enabled by default when I upgrade to Moodle 4.2 (providing I have configured my Moodle to connect to a Matrix homeserver).  So that going forward new courses have a better communication experience.
3. As an admin I want to be able to set a default for new courses to either have Matrix rooms created or not. To assist my teachers.