multi: replace FundingLocked and funding_locked strings

This commit is created by running the following commands,
```shell
find . -name "*.go" -exec sed -i '' 's/\"FundingLocked/\"ChannelReady/g' {} \;
find . -name "*.go" -exec sed -i '' 's/FundingLocked\"/ChannelReady\"/g' {} \;
find . -name "*.go" -exec sed -i '' 's/\ funding_locked/\ channel_ready/g' {} \;
```

funding/interfaces.go

@@ -23,15 +23,15 @@ type Controller interface {
 // aliasHandler is an interface that abstracts the managing of aliases.
 type aliasHandler interface {
 	// RequestAlias lets the funding manager request a unique SCID alias to
-	// use in the funding_locked message.
+	// use in the channel_ready message.
 	RequestAlias() (lnwire.ShortChannelID, error)
 
 	// PutPeerAlias lets the funding manager store the received alias SCID
-	// in the funding_locked message.
+	// in the channel_ready message.
 	PutPeerAlias(lnwire.ChannelID, lnwire.ShortChannelID) error
 
 	// GetPeerAlias lets the funding manager lookup the received alias SCID
-	// from the funding_locked message. This is not the same as GetAliases
+	// from the channel_ready message. This is not the same as GetAliases
 	// which retrieves OUR aliases for a given channel.
 	GetPeerAlias(lnwire.ChannelID) (lnwire.ShortChannelID, error)