cnct+sweeper: give contract court access to relay fee

Relay fee is needed later to sweep anchors at the minimum fee rate.

contractcourt/commit_sweep_resolver_test.go

@@ -10,6 +10,7 @@ import (
 	"github.com/lightningnetwork/lnd/chainntnfs"
 	"github.com/lightningnetwork/lnd/input"
 	"github.com/lightningnetwork/lnd/lnwallet"
+	"github.com/lightningnetwork/lnd/lnwallet/chainfee"
 	"github.com/lightningnetwork/lnd/sweep"
 )
 
@@ -120,6 +121,10 @@ func (s *mockSweeper) CreateSweepTx(inputs []input.Input, feePref sweep.FeePrefe
 	return nil, nil
 }
 
+func (s *mockSweeper) RelayFeePerKW() chainfee.SatPerKWeight {
+	return 253
+}
+
 var _ UtxoSweeper = &mockSweeper{}
 
 // TestCommitSweepResolverNoDelay tests resolution of a direct commitment output