lnrpc+rpcserver: add new field LockedIn for HTLCs

In this commit, we add a new field `LockedIn` on HTLCs so it can be used
to decide whether an HTLC found on the local commitment has been
committed on the remote commitment.

rpcserver.go

@@ -4842,6 +4842,14 @@ func createRPCOpenChannel(r *rpcServer, dbChannel *channeldb.OpenChannel,
 		)
 	}
 
+	// Create a set of the HTLCs found in the remote commitment, which is
+	// used to decide whether the HTLCs from the local commitment has been
+	// locked in or not.
+	remoteHTLCs := fn.NewSet[[32]byte]()
+	for _, htlc := range dbChannel.RemoteCommitment.Htlcs {
+		remoteHTLCs.Add(htlc.RHash)
+	}
+
 	for i, htlc := range localCommit.Htlcs {
 		var rHash [32]byte
 		copy(rHash[:], htlc.RHash[:])
@@ -4893,6 +4901,7 @@ func createRPCOpenChannel(r *rpcServer, dbChannel *channeldb.OpenChannel,
 			HtlcIndex:           htlc.HtlcIndex,
 			ForwardingChannel:   forwardingChannel,
 			ForwardingHtlcIndex: forwardingHtlcIndex,
+			LockedIn:            remoteHTLCs.Contains(rHash),
 		}
 
 		// Add the Pending Htlc Amount to UnsettledBalance field.