Develop flexible system event mapping support

As identified in the QSR 2.0 hazard analysis (technical hazard #8), the system event mapping could be evolved to support complex cases.

Currently the system events can only be mapped to one safety object and vice versa.

URL: https://intranet.qt.io/display/QTRD/QSR+2.0+Hazard+analysis+and+risk+management 

Design feature that fulfills the possible use case scenarios. Identify the needs proactively together with the stakeholders in the customer interface.

Definition of Done

1. Unit tests are implemented
2. Quality gates passed (reviews, coverage, optionally CVE).
3. TestRail entry done
4. API documentation done (for QML), comments added in code.
5. Architecture documentation is updated.
6. Design documentation is updated.