Returns the current state of a single static-audience upload (custom-properties or segments file). You
receive the full URL for this endpoint as the status field on the response of the corresponding ingest-url
endpoint. You can also build the URL yourself with the type and file query parameters described below.

The status field of the response reports where the upload is in its lifecycle. When it is completed,
the ingestedAt field carries the timestamp of completion. To know whether a specific forecast already
includes this upload, compare ingestedAt against forecastEnvironment.staticAudiencesSyncDateTime on the
forecast response. When staticAudiencesSyncDateTime >= ingestedAt, the snapshot the forecast used was
sampled after the upload was persisted, so the upload is reflected.