Summary:
Since new iOS is much more aggressive on killing apps, we cannot use random apps for our integrations tests anymore (as they get killed).
This diff adds app that uses some system hooks in order to avoid that (eg. by adding `unboundedTaskCompletion`, `continuous` as `UIBackgroundModes` in it's `Info.Plist`) and requesting background task via app delegate.
Reviewed By: antiarchit
Differential Revision: D8348520
fbshipit-source-id: e419774f09a30c57e0eedcb54efdaef10b2bfcc7
6f2db35b62