introduce [data-vue-app], fixes #4294

app/controllers/admin/cache.php

app/controllers/admin/courses.php

app/controllers/admin/tree.php

app/controllers/course/contentmodules.php

app/controllers/my_courses.php

app/controllers/search/courses.php

app/views/admin/cache/settings.php

app/views/admin/courses/index.php

app/views/admin/tree/batch_assign_semtree.php

app/views/admin/tree/rangetree.php

app/views/admin/tree/semtree.php

app/views/course/contentmodules/index.php

app/views/course/contentmodules/info.php

app/views/my_courses/index.php

app/views/search/courses/index.php

lib/classes/Debug/VueCollector.php

lib/classes/StudipController.php

lib/classes/VueApp.php

resources/assets/javascripts/bootstrap/admin-courses.js

resources/assets/javascripts/bootstrap/cache-admin.js