Refactored Info Bubble (show/hide/fade-in/fade-out)

Background
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The following actions have been factored out of InfoBubbleViewModel

* Show
* Hide
* Fade In
* Fade Out

These actions are view-only actions but were implemented as commands on **InfoBubbleViewModel**. I have moved them out of the **InfoBubbleViewModel** back into **InfoBubbleView** so that it makes the design cleaner.
Unit testing
============
* All existing test cases are passing