API level 22 is below 23 (aka Marshmallow), which included an overhaul in the
permissions system. React Native recommends 22 (it's the default when you create
a new app) and there have been reports when set higher [0] and [1].

This also fixes a critical bug, wherein Jitsi Meet wouldn't request permissions
for the camera and microphone.

Last, this change also allows us to get rid of the overlay checking code,
because it was only needed for API level 23 or higher.

[0]: https://github.com/facebook/react-native/pull/10479
[1]: https://github.com/facebook/react-native/issues/10587