Accept CDK constructs in `on_*` methods.

[gshpychka]

It would be great if we could pass a CDK construct in the on_* methods, instead of passing all the ARN parts. The boilerplate feels unnecessary.

[udondan]

It's a nice idea but I don't see a viable solution.

How would floyd know if a construct has an ARN and what is the properties name without manually implementing every available CDK construct?

Manually implementing every single construct seems to be a huge amount of work and the benefit is rather small, because passing an ARN is pretty straight forward, e.g. for a Lambda function: .on(fn.functionArn).