multi: rename FeePreference to FeeEstimateInfo

Results from running,
```
gofmt -d -w -r 'FeePreference -> FeeEstimateInfo' .
```

lnrpc/rpc_utils.go

@@ -222,7 +222,7 @@ func CalculateFeeRate(satPerByte, satPerVByte uint64, targetConf uint32,
 
 	// Based on the passed fee related parameters, we'll determine an
 	// appropriate fee rate for this transaction.
-	feePref := sweep.FeePreference{
+	feePref := sweep.FeeEstimateInfo{
 		ConfTarget: targetConf,
 		FeeRate:    satPerKw,
 	}

lnrpc/walletrpc/walletkit_server.go

@@ -965,7 +965,7 @@ func (w *WalletKit) BumpFee(ctx context.Context,
 			in.SatPerByte * 1000,
 		).FeePerKWeight()
 	}
-	feePreference := sweep.FeePreference{
+	feePreference := sweep.FeeEstimateInfo{
 		ConfTarget: uint32(in.TargetConf),
 		FeeRate:    satPerKw,
 	}