rpc: add channel reserve fields in RPC responses.

In this commit two fields were added to the Channl RPC result in both
open and pending states.
The fields: local_chan_reserve, remote_chan_reserve represents the
reservation the nodes are rquired to keep in both sides of the channel.
This is usefull when calculating the "real" inbound and outbound
liquidity in an accurate way.

rpcserver.go

@@ -2232,11 +2232,13 @@ func (r *rpcServer) PendingChannels(ctx context.Context,
 
 		resp.PendingOpenChannels[i] = &lnrpc.PendingChannelsResponse_PendingOpenChannel{
 			Channel: &lnrpc.PendingChannelsResponse_PendingChannel{
-				RemoteNodePub: hex.EncodeToString(pub),
-				ChannelPoint:  pendingChan.FundingOutpoint.String(),
-				Capacity:      int64(pendingChan.Capacity),
-				LocalBalance:  int64(localCommitment.LocalBalance.ToSatoshis()),
-				RemoteBalance: int64(localCommitment.RemoteBalance.ToSatoshis()),
+				RemoteNodePub:        hex.EncodeToString(pub),
+				ChannelPoint:         pendingChan.FundingOutpoint.String(),
+				Capacity:             int64(pendingChan.Capacity),
+				LocalBalance:         int64(localCommitment.LocalBalance.ToSatoshis()),
+				RemoteBalance:        int64(localCommitment.RemoteBalance.ToSatoshis()),
+				LocalChanReserveSat:  int64(pendingChan.LocalChanCfg.ChanReserve),
+				RemoteChanReserveSat: int64(pendingChan.RemoteChanCfg.ChanReserve),
 			},
 			CommitWeight: commitWeight,
 			CommitFee:    int64(localCommitment.CommitFee),
@@ -2647,6 +2649,8 @@ func createRPCOpenChannel(r *rpcServer, graph *channeldb.ChannelGraph,
 		CsvDelay:              uint32(dbChannel.LocalChanCfg.CsvDelay),
 		Initiator:             dbChannel.IsInitiator,
 		ChanStatusFlags:       dbChannel.ChanStatus().String(),
+		LocalChanReserveSat:   int64(dbChannel.LocalChanCfg.ChanReserve),
+		RemoteChanReserveSat:  int64(dbChannel.RemoteChanCfg.ChanReserve),
 	}
 
 	for i, htlc := range localCommit.Htlcs {