Make components instances instead of static classes

It would be really nice if we could make the components be actual instances, one per element, instead of classes containing a bunch of static methods. We could start this refactoring by taking a look at `PasswordRevealIndicator`, since that needs a little TLC anyway, and it wouldn't cause a break in the hierarchy chain.

I think what we should do is have every component derive from a superclass, `Component`, so that we can control some of this common behavior in a polymorphic way.