Workflow usage statistics

Add an endpoint for a workflow where customizable usage statistics can be fetched.

changed milestone to %Version 1.0.0

added Workflow WorkflowExecution labels

assigned to @daniel.goebel

mentioned in issue clowm-ui#48 (closed)

marked this issue as related to clowm-ui#48 (closed)

created branch feature/24-workflow-usage-statistics to address this issue

mentioned in merge request !30 (merged)

mentioned in commit 68b6beda

mentioned in commit c8b5d24e

mentioned in commit 038cbee7

closed with merge request !30 (merged)