Support onBind/onUnbind listeners on generated models

[elihart]

Generated models now include onBind and onUnbind builder style method that takes a callback listener. When the model hits these lifecycle events the listener will be called with the model and view that was bound.

This looks like

new LoaderModel_()
       .onBind((model, view) -> loadMore())
       .addTo(this);

The goal is to avoid having one adapter method for handling onModelBound, and instead keeping the logic where the model is created.

This involved quite a bit change to the processor to generate the correct interface, store the listener fields, update hashCode/equals, etc. Also had to update all the tests.

Since I was updating all the tests and figuring out a good way to do this, I realized a better way to do the model click listener handling as well without storing the viewholder and bound object on the model. This seems cleaner and safer.

[elihart]

@gpeal @ngsilverman

[ngsilverman]

Love it. 👍