OCPP201: Publish websocket connection state

[Pietfried]

Describe your changes

Added connection_status_changed_callback to OCPP201 to publish this information over the ocpp interface

Issue ticket number and link

Companion PR in libocpp: https://github.com/EVerest/libocpp/pull/693

Checklist before requesting a review

• [x] I have performed a self-review of my code
• [ ] I have made corresponding changes to the documentation
• [x] I read the contribution documentation and made sure that my changes meet its requirements