Change detection of label-like activities to an easier way

[Stefan Hanauska]

Recently I created an activity type which can be configured to show on the course page (like a label) or on a separate page (with view-link) by the user. The current approach to handle label-like activities provides no suitable way for this use case.

My proposal: Remove $labellikecoursemods and check has_view() in cm_info instead (PR incoming).