ChainFeeUpdateAggregator aggregates a slice of ChainFeeUpdates into a single Update by taking the median of each price component and the timestamps.

FromPackedFee creates a new Update @param packedFee: Is the fee components packed into a single big.Int packedFee = (dataAvFeeUSD << 112) | executionFeeUSD.

AggregateObservation is the aggregation of a list of observations.