Add Invoke method to signal descriptor

[badcel]

Add Invoke method to signal descriptor

Sample implementation for signals without SignalArgs:

    public void Emit(TSender sender)
    {
        var instance = new Value(sender);
        var args = Internal.ValueArray2OwnedHandle.Create([instance]);
        Functions.SignalEmitV(...);
    }

[badcel]

For this to work there must be the binding for signal_emitv be generated. As this is not yet available this point needs to be postponed as I thought this would be an easy add which it is not anymore.