implement cms plugin to display working groups

this MR adds a CMS plugin to display selected or all activities as cards or badges.

merged

assigned to @philipp.sommer

enabled an automatic merge when the pipeline for 2bb8f199 succeeds

aborted the automatic merge because source branch was updated

added 1 commit

• 7d0f3788 - implement cms plugin to display working groups

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enabled an automatic merge when the pipeline for 7d0f3788 succeeds

mentioned in commit 681ee3d8

mentioned in merge request !146 (merged)