Cluster
This commit adds a new interface `Cluster` to manage cluster-level inputs grouping. This new interface replaces the `inputCluster` and will be futher refactored so the sweeper can use a much smaller coin selection lock.
UtxoAggregator
MaxFeeRate
SatPerVbyte
DetermineFeePerKw
Estimate
testify/mock
MockSweeperStore
GetTx
DeleteTx
TxRecord
FeePreference
FeeEstimateInfo