* Add GetUdi() extension methods for IUser and IUserGroup
* Add GetUdi() extension methods for IRelation
* Move GetUdi() extension methods for Script and Stylesheet to interface types
* Register relation, user and user-group as known UDI types
* Obsolete UdiParserServiceConnectors
* Use IScript and IStylesheet types in tests
* Fix UdiTests after obsoleting UdiParserServiceConnectors
* Fix IWebhook and IEntity GetUdi extension method
* Refactor to use switch expressions
* Add GetUdiForWebhook test
* Added a webhook builder for unit tests.
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Co-authored-by: Andy Butland <abutland73@gmail.com>