Summary:
Flipper Launcher downloads, unpacks, launches Flipper, and closes itself.
This is fine except for the fact that Flipper may be initiating and thus there's a gap of a few seconds until engineers see the main Flipper UI.
This change improves this by launching earlier, even if just showing a loading page until Flipper is actually ready.
Reviewed By: passy, aigoncharov
Differential Revision: D48824479
fbshipit-source-id: aa6147a09f313d80592c9b08d089660ba73773a4
2858259497