firebase-ios-sdk

Fix crash when displaying UIAlertController for a test on device message that errored (#4446)

* Use application delegate window to show test on device error alert, run on main thread

* Refactor the display of the test on device error alert to use a window on the foregrounded scene

* More descriptive variable name for the view controller used to present the error alert

* Import UIKit at the top of FIRIAMDisplayExecutor.m

* Early return in test on device error flow if there's no foregrounded scene

* scripts/styles.sh