[EPIC] Create a Kanban Backend

[Zitrone44]

Goal
An API should be added allowing groups (#1487) to create Create, Update, Delete Kanban, Boards.
Each board should have four columns Backlog, Doing, In Review, Done. These columns do not need to be dynamic on a per board basis. For each board tasks should be able to Create, Update, Delete and sorted into these columns.

Information
This should be implemented in Kotlin. The code used for the Playground can be used as a Template. New Controllers, Models etc. in diffent files must be created.