Made IView Interface and ViewWrapper class public, Exposed Logger.Write Method (#263)

[HeedfulCrayon]

Description

Made the MvvmDialogs library extendable to that people could implement their own DialogServiceViews-like class and DialogService class that utilizes that collection of registered views. This allows for people to use a thread-safe collection when running an application with multiple UI threads.

• Fixes #263

Checklist

• [✔] My code follows the style guidelines of this project
• [✔] I have performed a self-review of my own code
• [✔] I have commented my code, particularly in hard-to-understand areas
• [N/A] I have made corresponding changes to the documentation
• [N/A] I have added tests that prove my fix is effective or that my feature works

[HeedfulCrayon]

I figured this PR was easier to swallow than a refactor of DialogServiceViews to use a ConcurrentDictionary. That way anyone else can use whatever collection they want that fits their specific needs.