set default icon size to 20, fixes #2801

.stylelintrc.json

app/controllers/admin/courses.php

app/controllers/admin/role.php

app/controllers/admin/statusgroups.php

app/controllers/course/files.php

app/controllers/course/grouping.php

app/controllers/course/members.php

app/controllers/course/room_requests.php

app/controllers/course/studygroup.php

app/controllers/files.php

app/controllers/files_dashboard/helpers.php

app/controllers/files_dashboard/sidebar.php

app/controllers/help_content.php

app/controllers/institute/files.php

app/controllers/institute/members.php

app/controllers/messages.php

app/controllers/my_ilias_accounts.php

app/controllers/oer/admin.php

app/controllers/privacy.php

app/controllers/profile.php