Enum types are not used for arguments and properties in the api.json

Question about `api.json`:
Why enum types are presented as such only in `return_type` and shown as `int` everywhere else?

Random example: `OS` has [`screen_orientation`](https://github.com/godotengine/godot/blob/87aa694ae5003af797b3a1de56f6d4579997bb47/doc/classes/OS.xml#L1093) property with type of enum `OS.ScreenOrientation`, but this enum is presented only in `return_type` for getter, while `set_screen_orientation` has an argument `orientation` of type `int` and property itself typed as `int` too.

In documentation there is no such discrepancy everything that is enum has `enum` attribute.