lnwallet + funding: move funding tx publish to fundingmgr

This commit moves the responsibility for publishing the funding tx to
the network from the wallet to the funding manager. This is done to
distinguish the failure of completing the reservation within the wallet
and failure of publishing the transaction.

Earlier we could fail to broadcast the transaction, which would cause us
to fail the funding flow. This is not something we can do directly,
since the CompeteReservation call will mark the channel IsPending in the
databas.e

lnwallet/reservation.go

@@ -4,12 +4,12 @@ import (
 	"net"
 	"sync"
 
-	"github.com/lightningnetwork/lnd/channeldb"
-	"github.com/lightningnetwork/lnd/lnwire"
 	"github.com/btcsuite/btcd/btcec"
 	"github.com/btcsuite/btcd/chaincfg/chainhash"
 	"github.com/btcsuite/btcd/wire"
 	"github.com/btcsuite/btcutil"
+	"github.com/lightningnetwork/lnd/channeldb"
+	"github.com/lightningnetwork/lnd/lnwire"
 )
 
 // ChannelContribution is the primary constituent of the funding workflow
@@ -434,11 +434,11 @@ func (r *ChannelReservation) OurSignatures() ([]*InputScript, []byte) {
 // https://github.com/bitcoin/bips/blob/master/bip-0069.mediawiki.
 // Additionally, verification is performed in order to ensure that the
 // counterparty supplied a valid signature to our version of the commitment
-// transaction.  Once this method returns, caller's should then call
-// .WaitForChannelOpen() which will block until the funding transaction obtains
-// the configured number of confirmations. Once the method unblocks, a
-// LightningChannel instance is returned, marking the channel available for
-// updates.
+// transaction.  Once this method returns, caller's should broadcast the
+// created funding transaction, then call .WaitForChannelOpen() which will
+// block until the funding transaction obtains the configured number of
+// confirmations. Once the method unblocks, a LightningChannel instance is
+// returned, marking the channel available for updates.
 func (r *ChannelReservation) CompleteReservation(fundingInputScripts []*InputScript,
 	commitmentSig []byte) (*channeldb.OpenChannel, error) {