Add litho sample app to arc-focus-large
Add litho sample app to arc-focus-large

Summary: We point people to our sample app for API demos but currently it takes ~5 mins to get the IDE to recognize the files.

Reviewed By: cute-jumper

Differential Revision: D24162074

fbshipit-source-id: 923b2ef17686b4526b55abff4059f82cc37da082

facebook/litho,facebook/litho,facebook/litho,facebook/litho,facebook/litho,facebook/litho