Generic operation handler for main and child devices

[reubenmiller]

The main devices support the configuration of a custom operation handler the main device. Therefore it makes sense adding support for easily creating a custom operation handler/mapper for operations dedicated for child devices to enable maximum flexibility.

The concept for the main device could be changed to support a more generic implementation which could either execute a script or publish on a specific topic based on the user-defined config.

Overview

• Support configuring which operation request types should be published to child device topics
• Managed operation requests (e.g. timeout, status transitions from pending ➡️ executing ➡️ successful or failed)

[reubenmiller]

Functional duplicate of https://github.com/thin-edge/thin-edge.io-roadmap/issues/68