lntest: allow node restore by extended root key

To allow testing restoring a node from an extended master root key, we
add an extra argument to the RestoreNodeWithSeed function.

lntest/harness.go

@@ -426,7 +426,7 @@ func (n *NetworkHarness) newNodeWithSeed(name string, extraArgs []string,
 // will finish initializing the LightningClient such that the HarnessNode can
 // be used for regular rpc operations.
 func (n *NetworkHarness) RestoreNodeWithSeed(name string, extraArgs []string,
-	password []byte, mnemonic []string, recoveryWindow int32,
+	password []byte, mnemonic []string, rootKey string, recoveryWindow int32,
 	chanBackups *lnrpc.ChanBackupSnapshot,
 	opts ...NodeOption) (*HarnessNode, error) {
 
@@ -441,6 +441,7 @@ func (n *NetworkHarness) RestoreNodeWithSeed(name string, extraArgs []string,
 		WalletPassword:     password,
 		CipherSeedMnemonic: mnemonic,
 		AezeedPassphrase:   password,
+		ExtendedMasterKey:  rootKey,
 		RecoveryWindow:     recoveryWindow,
 		ChannelBackups:     chanBackups,
 	}