[nikobus] fixed refresh handling (#9114)

[nikobus] fixed refresh handling (#9114)

* * fixed refresh handing due `channelLinked` not called anymore on startup for example (similar to https://github.com/openhab/openhab-core/issues/1707),
* "Impacted Modules" can be empty if button is configured as "standalone" and does not impact modules,
* minor doc fix

* * check if configured impacted module for `impactedModules` is referencing an existing thing,
* fixed warnings
* Fixed review comment.

Signed-off-by: Boris Krivonog <boris.krivonog@inova.si>