[native] Fix KeyboardAvoidingView animation when cross-fade animation…

…s enabled on iOS

Summary: Fixes [ENG-5919](https://linear.app/comm/issue/ENG-5919/enabling-cross-fade-transitions-on-ios-makes-app-unusable), which is [this React Native issue](facebook/react-native#29974). I took the patch there as inspiration, but there are minimal differences because we have our own `KeyboardAvoidingView` (which lets us skip using `patch-package`).

Test Plan: Confirm that the repro no longer works: open chat, select `ChatInputBar`, swipe back

Reviewers: atul, ginsu, tomek

Reviewed By: ginsu

Differential Revision: https://phab.comm.dev/D10120

native/components/keyboard-avoiding-view.react.js

@@ -122,7 +122,7 @@ class InnerKeyboardAvoidingView extends React.PureComponent<Props, State> {
 
   get relativeKeyboardHeight(): number {
     const { viewFrame, keyboardFrame } = this;
-    if (!viewFrame || !keyboardFrame) {
+    if (!viewFrame || !keyboardFrame || keyboardFrame.screenY === 0) {
       return 0;
     }
     return Math.max(viewFrame.y + viewFrame.height - keyboardFrame.screenY, 0);