Validate BehaviorBase<T> and what is needed (if anything) beyond Behavior<T>

We probably want to file an issue about re-checking all this, as I know some of the original issues I believe were fixed in the underlying behaviors package, but I think we still do some extra logic here.

Probably a thing where when we can better test these and shore that up, we could try removing the intermediate class and see what happens or if anything breaks. (Assuming we have enough coverage)

_Originally posted by @michael-hawker in https://github.com/CommunityToolkit/Windows/pull/20#discussion_r1167170975_

Related Toolkit Discussion: https://github.com/CommunityToolkit/WindowsCommunityToolkit/issues/3856

with specifically more prior context and links here: https://github.com/CommunityToolkit/WindowsCommunityToolkit/issues/3856#issuecomment-801471909

関連するToolkit Discussionとリンクされた以前のコンテキストから始め、次にBehaviorBaseとBehaviorを比較して、ここに残っている追加のロジックを特定します。動作を壊さずに中間クラスを削除できるか評価する前に、十分なテストカバレッジを確立してください。

索引モデルが issue の本文から書いたものです。