channeldb/channel: add property ChanStatus in place of IsBorked to OpenChannel

This commit changes the bool `IsBorked` in OpenChannel to a `ChanStatus`
struct, of type ChannelStatus. This is used to indicated that a channel
that is technically still open, is either borked, or has had a
commitment broadcasted, but is not confirmed on-chain yet.

The ChannelStatus type has the value 1 for the status Borked, meaning it
is backwards compatible with the old database format.

lnwallet/channel.go

@@ -4754,7 +4754,7 @@ func NewUnilateralCloseSummary(chanState *channeldb.OpenChannel, signer Signer,
 		RemotePub:      chanState.IdentityPub,
 		Capacity:       chanState.Capacity,
 		SettledBalance: localBalance,
-		CloseType:      channeldb.ForceClose,
+		CloseType:      channeldb.RemoteForceClose,
 		IsPending:      true,
 	}