* Adding contentType to navigation node
* Loading contentType from DB
* Considering contentTypeKey when adding a navigation node & fixing references
* Using IContentTypeBaseService to load content types
* Adding generics to ContentNavigationServiceBase and fixing references
* Adding TryGetChildrenKeysOfType and implementation
* Refactoring test data
* Adding unit tests for TryGetChildrenKeysOfType
* Update CreateContentCreateModel in tests to receive content type
* Fix references
* Cleanup
* Adding integration tests for TryGetChildrenKeysOfType
* Cleanup
* Cleanup
* Descendants of type implementation
* Descendants of type tests
* Interface updates
* Ancestors of type implementation and tests
* Siblings of type implementation and tests
* Cleanup
* Integration tests
* Adding root of type implementation and tests
* Fix Ancestors extension methods
* Fix descendants extension methods
* Fix children extension methods
* Fix siblings extension methods
* Add helper methods
* Fix a bug
* Fixed unit tests by setting up mocks
* Adding missing extension method
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Co-authored-by: Bjarke Berg <mail@bergmania.dk>