Bug Report: LabelerServices.toJson does not save type

[JetA2]

Hi,

Thank you for this excellent library!

I would like to save the moderation preferences to use for moderation when offline.
I ran into a problem which seems to be caused by the following bug:

Bug Behavior

When a LabelerServices object is saved as JSON, the type is not saved for the views.
When the object is deserialized, the views are created with the "unknown" type.

Expected Behavior

A serialized LabelerServices object can be deserialized to an identical object.

Step to Reproduce

final prefs = await service.actor.getPreferences();
final moderationPrefs = prefs.data.getModerationPrefs();

final services = await service.labeler.getServices(
  dids: moderationPrefs.moderationLabelers,
  detailed: true,
  headers: moderationPrefs.labelerHeaders,
);
final testJson = services.data.toJson();
final testObject = LabelerServices.fromJson(testJson);

assert(services.data == testObject);