1. Refactored alwaysVisible into InfoBubbleState to more clearly represent the action
2. Refactored SetAlwaysVisibleCommand into ChangeInfoBubbleStateCommand
1. Refactored isShowPreviewByDefault, which is wrongly used, away from InfoBubbleViewModel
Added a Loaded event handler to set up initial visibility and opacity of info bubble
Added initial value to resolve binding expression error.
Code cleanup
Merge pull request #858 from kah-heng/PreviewOffsetAfterSwitchFix_ChocoButterUI

Merging this in since it is meant to fix a very important behavioral issue of info bubble across tabs.