ChanUpgradeAck should call the chanUpgradeOpen subprotocol if ready

[damiannolan]

Summary

The following spec additions should be added to the ChanUpgradeAck handler to call the channel upgrade open subprotocol if ready:

// if both sides have already flushed then open the upgrade handshake immediately
if currentChannel.flushStatus == FLUSHCOMPLETE && counterpartyFlushStatus == FLUSHCOMPLETE {
        openUpgradelHandshake(portIdentifier, channelIdentifier)
        module.onChanUpgradeOpen(portIdentifier, channelIdentifier)
}

Note, we normally route app callbacks from the core msg server so we probably need to make this check at that level in order to call:

cbs.OnChanUpgradeOpen(ctx, msg.PortId, msg.ChannelId)

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For Admin Use

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• Appropriate labels applied
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[damiannolan]

Note when calling into ChanUpgradeOpen subprotocol from ChanUpgradeAck we assume the counterpartyChannelState to be TRYUPGRADE as is already verified in the ChanUpgradeAck handler

func (k Keeper) ChanUpgradeOpen(
	ctx sdk.Context,
	portID,
	channelID string,
	counterpartyChannelState types.State,
	proofChannel []byte,
	proofHeight clienttypes.Height,
) error 

[DimitrisJim]

closed in #4075