Simplify ComponentsHalogenHooks

[milesfrain]

I was initially confused about how ButtonMessage was being used, and then realized that the component's output value is simply ignored by the parent when incrementing toggle count. So this can be replaced with Unit. Don't know whether this makes things more or less confusing. We could alternatively go with an Output alias and some more comments.

[JordanMartinez]

Nah, that's fine. Using unit is better.