Refactor `Redraw` - Non-virtual with the right set of virtual `OnXXX` methods

[tig]

In v2, i'd like us to revisit how Redraw and the related events are structured. I started this in my View2 PR...

* `Redraw` is mis-named. It should just be `Draw` (it also shouldn't take a `Bounds` because implementors can just use `this.Bounds`; this is a cause of a bunch of bugs BTW).

* `Draw` should simply call
  
  * `OnDraw`
  * `OnDrawFrames`
  * `OnDrawContent`
  * `OnDrawContentComplete`

Each of those invokes an event and each is cancellable (except OnDrawContentComplete).

@tig I agree with this scenario, but Draw mustn't be virtual to avoid derived class not calling the OnDraw, OnDrawFrames, OnDrawContent and OnDrawContentComplete. Maybe protected. What do you think?

Originally posted by @BDisp in #2479 (comment)

[tig]

This was addressed.