multi: move unit test backend funcs to new package

To avoid circular dependency issues between packages, we move the unit
test backend creation function to a new package in the lntest parent
package.

routing/chainview/interface_test.go

@@ -25,9 +25,9 @@ import (
 	_ "github.com/btcsuite/btcwallet/walletdb/bdb" // Required to register the boltdb walletdb implementation.
 	"github.com/lightninglabs/neutrino"
 	"github.com/lightningnetwork/lnd/blockcache"
-	"github.com/lightningnetwork/lnd/chainntnfs"
 	"github.com/lightningnetwork/lnd/channeldb"
 	"github.com/lightningnetwork/lnd/kvdb"
+	"github.com/lightningnetwork/lnd/lntest/unittest"
 	"github.com/lightningnetwork/lnd/lntest/wait"
 	"github.com/stretchr/testify/require"
 )
@@ -482,7 +482,7 @@ func testFilterBlockDisconnected(node *rpctest.Harness,
 
 	// Create a node that has a shorter chain than the main chain, so we
 	// can trigger a reorg.
-	reorgNode := chainntnfs.NewMiner(
+	reorgNode := unittest.NewMiner(
 		t, netParams, []string{"--txindex"}, true, 5,
 	)
 
@@ -984,7 +984,7 @@ func TestFilteredChainView(t *testing.T) {
 	// dedicated miner to generate blocks, cause re-orgs, etc. We'll set up
 	// this node with a chain length of 125, so we have plenty of BTC to
 	// play around with.
-	miner := chainntnfs.NewMiner(
+	miner := unittest.NewMiner(
 		t, netParams, []string{"--txindex"}, true, 25,
 	)