Creating inner types inside classes

[elifKurtay]

Feature description

It would be nice to be able to create inner types inside classes. The current PropertyDef or FieldDef seems limited to creating variables and does not allow adding records, enums, or inner classes inside a class.

An example generation goal could be the following record:

public record LlamaRecord(
    @NotNull @Min(0) int age,
    Status status
) {
  enum Status {
    Single,
    Taken
  }
}