Dump a JSON file about properties of generated DSE test cases

General

The JSON file shall be dumped in the runtime WS to ease its discovery. Also, a separate file ensures that the generated information is not cluttered with other log messages.

Properties to include

• Number of Components
• Number of Generated constraints (per Constraint)
• List of Constraint names

(from redmine: issue id 4048, created on 2020-07-24, closed on 2020-10-20)