[TIMOB-11458] iOS: Accessibility: hide TiUIWindow when another window opens on top; send accessibility notification about screen update
[TIMOB-11335] Animate gradientLayer opacity
fix bad merge
Merge pull request #3663 from euforic/timob-11794

fix bad merge for [#TIMOB-11794]
Merge pull request #3661 from vishalduggal/timob-11335

[TIMOB-11335] Animate gradientLayer opacity
Merge pull request #3603 from mstepanov/timob-11458

[TIMOB-11458] iOS: Accessibility: hide TiUIWindow when another window opens on top; send accessibility notification about screen update