Merge CommonUtilities into Helper.
Move global error handler functions into Helper.
Namespace ListViewHelpers.
TestComponents => Helper.ItemsManager
Rename UnitTestsCommon.ts to Helper.ItemsManager.ts
Rename util.ts => Helper.ts
Rename ListViewHelpers.ts => Helper.ListView.ts
ListViewUtils => Helper.ListView.Utils
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Merge branch 'master' into AmazingJaze/listviewstriping

Conflicts:
	tests/ListViewComponents/VirtualizeContentsViewTest.ts