multi: move Input interface and related code

This commit is a step to split the lnwallet package. It puts the Input
interface and implementations in a separate package along with all their
dependencies from lnwallet.

contractcourt/chain_watcher.go

@@ -14,6 +14,7 @@ import (
 	"github.com/davecgh/go-spew/spew"
 	"github.com/lightningnetwork/lnd/chainntnfs"
 	"github.com/lightningnetwork/lnd/channeldb"
+	"github.com/lightningnetwork/lnd/input"
 	"github.com/lightningnetwork/lnd/lnwallet"
 )
 
@@ -93,7 +94,7 @@ type chainWatcherConfig struct {
 	// signer is the main signer instances that will be responsible for
 	// signing any HTLC and commitment transaction generated by the state
 	// machine.
-	signer lnwallet.Signer
+	signer input.Signer
 
 	// contractBreach is a method that will be called by the watcher if it
 	// detects that a contract breach transaction has been confirmed. Only
@@ -191,13 +192,13 @@ func (c *chainWatcher) Start() error {
 
 	localKey := chanState.LocalChanCfg.MultiSigKey.PubKey.SerializeCompressed()
 	remoteKey := chanState.RemoteChanCfg.MultiSigKey.PubKey.SerializeCompressed()
-	multiSigScript, err := lnwallet.GenMultiSigScript(
+	multiSigScript, err := input.GenMultiSigScript(
 		localKey, remoteKey,
 	)
 	if err != nil {
 		return err
 	}
-	pkScript, err := lnwallet.WitnessScriptHash(multiSigScript)
+	pkScript, err := input.WitnessScriptHash(multiSigScript)
 	if err != nil {
 		return err
 	}