async fn decode_remap_data_until_geq_external_frontier<FromTime: SourceTimestamp, T: Timestamp + Lattice + TotalOrder + Codec64 + From<EpochMillis> + Sync>(
    id: GlobalId,
    external_frontier: Antichain<FromTime>,
    as_of: Antichain<T>,
    remap_subscribe: Subscribe<SourceData, (), T, Diff>,
) -> Result<T, StorageError<T>>