* Adds v2 spec additionalproperties examples, adds v3 spec nulllable model example, updates samples
* Remaining samples updates
* Adds csharp generator update to handle models with multilevel parent types, which works for the AdditionalPropertiesObject model, samples updated
* Run ./bin/utils/ensure-up-to-date to re-generate samples run in the CI.
* Fixed the #1088 issue by removing the update of enumeration properties while processing objects that reference them. Launched the ./bin/csharp-petstore-all.sh script.
