Deprecate `StudipAutoloader` and use composer's `autoload`

app/controllers/questionnaire.php

composer.json

composer.lock

db/migrations/1.2_step_102_datenfeldtypen.php

db/migrations/1.6_step_25_raumzeit_db_conversion.php

...issionrules/conditionaladmission/ConditionalAdmission.php

...sionrules/coursememberadmission/CourseMemberAdmission.php

lib/admissionrules/limitedadmission/LimitedAdmission.php

lib/admissionrules/lockedadmission/LockedAdmission.php

...antrestrictedadmission/ParticipantRestrictedAdmission.php

lib/admissionrules/passwordadmission/PasswordAdmission.php

...sionrules/preferentialadmission/PreferentialAdmission.php

lib/admissionrules/termsadmission/TermsAdmission.php

lib/admissionrules/timedadmission/TimedAdmission.php

lib/bootstrap-autoload.php

lib/bootstrap.php

lib/calendar/CalendarColumn.php

lib/calendar/CalendarView.php

lib/calendar/CalendarWeekView.php

lib/classes/AdminCourseFilter.php