Shell enhancements for Attributes, Events and Comments (#671)
* Add generic attribute/event/command handling
* Optimize Subscription commands in shell
* Fix output for configuration data
* Enhance readme
* Enhance ValidationError to track fieldName
* Enhance ValidationError to track fieldName
* Add name in missing place
* typo
* Address review feedback
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Co-authored-by: lauckhart <greg@lauckhart.com>