prevent many warnings regarding php8 on main, fixes #4631

app/controllers/admission/courseset.php

app/controllers/course/members.php

app/controllers/institute/members.php

app/controllers/messages.php

app/controllers/multipersonsearch.php

app/controllers/my_courses.php

app/controllers/resources/room_request.php

app/views/admin/cronjobs/logs/index.php

app/views/course/enrolment/apply.php

app/views/course/management/lock.php

app/views/course/members/awaiting_list.php

app/views/course/room_requests/request_show_summary.php

app/views/course/wizard/steps/advancedbasicdata/index.php

app/views/file/add_url.php

app/views/file/choose_file.php

app/views/file/choose_folder_from_course.php

app/views/file/edit.php

app/views/file/edit_urlfile.php

app/views/file/update.php

app/views/institute/members/_table_body.php