`hierarchies-react`: `GenericErrorInfo.type` should not be "Unknown"

[grigasp]

I think "Unknown" is misleading, since it's supposed to be used by consumers to assign nodes their own types of errors. Those errors are unknown to us, but they are known to consumers. Example:

return {
  type: "Unknown",
  message: translate("resourcesBrowser.errors.resourceObjectNotSupportedByViewport"),
  id: object.id,
  isNodeExpandable: true,
  additionalData: { object, error: { type: "ResourceNotSupported" } } satisfies ResourceTreeError,
};

I think the type should be changed to something else, maybe "Generic"?