Add Moodle 4.5 (405) support

[Fragonite]

Prerequisites

This merge request should be applied after #36.

Summary

The plugin requires the before_http_headers hook in order to be compatible with Moodle 4.5.

The hook calls the original function for backwards compatibility with 4.1.

Testing

1. Install the plugin on Moodle 4.5 with both globally applied on courseinfo page #36 and this patch.
2. Add an instance of the block to a course with teachers.
3. Edit the block settings to show contact information for all teacher roles.
4. Verify it works correctly.
5. Verify the plugin admin settings page works correctly.