Feature Request: Support for JsonNullable

[pstawinski]

It would be great if generator supports JsonNullable from https://github.com/OpenAPITools/jackson-databind-nullable project.

So that JsonNullable<T> variable is threaten just as it was T variable and translated to variable: T in a typescript file.

It would allow to use generated typescript entities in partial patch updates as described in https://kdrozd.pl/how-to-perform-a-partial-update-patch-with-explicit-null/