sweep+walletrpc+lncli: report requested fee preference for pending sweeps

Previously only the fee rate used for the last sweep (the sweep bucket
average) was reported. This commit adds the request fee preference to
the report, which is used to select a bucket and the sweep tx fee rate.

sweep/sweeper.go

@@ -146,6 +146,9 @@ type PendingInput struct {
 	// NextBroadcastHeight is the next height of the chain at which we'll
 	// attempt to broadcast a transaction sweeping the input.
 	NextBroadcastHeight uint32
+
+	// Params contains the sweep parameters for this pending request.
+	Params Params
 }
 
 // bumpFeeReq is an internal message we'll use to represent an external caller's
@@ -1034,6 +1037,7 @@ func (s *UtxoSweeper) handlePendingSweepsReq(
 			LastFeeRate:         pendingInput.lastFeeRate,
 			BroadcastAttempts:   pendingInput.publishAttempts,
 			NextBroadcastHeight: uint32(pendingInput.minPublishHeight),
+			Params:              pendingInput.params,
 		}
 	}