add new webpack vue entrypoint for activity

+ rename existing activity.scss
+ rename webpack vue accompanyingCourse entrypoint

src/Bundle/ChillPersonBundle/Resources/views/AccompanyingCourse/edit.html.twig

@@ -15,5 +15,5 @@
       window.accompanyingCourseId = {{ accompanyingCourse.id|e('js') }};
       window.vueRootComponent = 'app';
    </script>
-   {{ encore_entry_script_tags('accompanying_course') }}
+   {{ encore_entry_script_tags('vue_accourse') }}
 {% endblock %}