channeldb+lnwallet: define Initiator for OpenChannel and LightningChannel

This commit introduces a new API to return information on which party opened
the channel using the new ChannelParty type. It does not change the underlying
structure of how we store this information.

Author: ProofOfKeags

channeldb/channel.go

@@ -889,6 +889,18 @@ func (c *OpenChannel) String() string {
 	)
 }
 
+// Initiator returns the ChannelParty that originally opened this channel.
+func (c *OpenChannel) Initiator() lntypes.ChannelParty {
+	c.RLock()
+	defer c.RUnlock()
+
+	if c.IsInitiator {
+		return lntypes.Local
+	}
+
+	return lntypes.Remote
+}
+
 // ShortChanID returns the current ShortChannelID of this channel.
 func (c *OpenChannel) ShortChanID() lnwire.ShortChannelID {
 	c.RLock()

lnwallet/channel.go

@@ -8709,6 +8709,14 @@ func (lc *LightningChannel) ChanType() channeldb.ChannelType {
 	return lc.channelState.ChanType
 }
 
+// Initiator returns the ChannelParty that originally opened this channel.
+func (lc *LightningChannel) Initiator() lntypes.ChannelParty {
+	lc.RLock()
+	defer lc.RUnlock()
+
+	return lc.channelState.Initiator()
+}
+
 // FundingTxOut returns the funding output of the channel.
 func (lc *LightningChannel) FundingTxOut() *wire.TxOut {
 	lc.RLock()