fix: native alert crash (#178)

## 📜 Description

Fixed a crash on iOS 16.5 when native alert is getting shown.

## 💡 Motivation and Context

The original exception occurred because of this error:

```bash
libc++abi: terminating due to uncaught exception of type folly::json::print_error: folly::toJson: JSON object value was an INF when serializing value at "progress"
```

`progress` was `inf` because in:

```swift
onEvent("onKeyboardMove", keyboardPosition as NSNumber, keyboardPosition / CGFloat(keyboardHeight) as NSNumber)
```

`keyboardHeight` variable was `0`. When we were trying to divide any
number by `0` in swfit we get `Inf` value, and this value can not be
serialised to JS equivalent.

The reason why this value becomes `0` is the fact that we have next
chain of calls:

```
keyboardWillHide
keyboardDidHide <- here we are setting keyboardHeight=0
keyboardWillHide <- here we setup CADisplayLink and after 16ms the crash will occur
keyboardDidHide
```

Based on output from above I had 3 options on how to fix the error:

### 1. Add `.isFinite` check

Good option, but it will prevent sending `onMove` event, though
according to values from `CADisplayLink` movement actually happens. So
we will kind of ignore actual information and it's not something that
satisfy me, because it may produce other bugs in the future.

### 2. Update `keyboardHeight` in `keyboardWillHide`

This variant also prevents a crash, but `progress` value in `onMove`
sometimes can be higher than `1` (in my tests sometimes it was 1.3+).
And it also seems like it gives incorrect calculation, because it's
strange to see progress > 1, when keyboard simply hides 🤷‍♂️

### 3. Don't set `keyboardHeight` to `0`

To come back to `1.4.x` behaviour, we don't need to reset
`keyboardHeight` to `0`. But I've added this code intentionally in
`1.5.0`, because in KV observer we are checking that keyboard should be
open and not animating:

```swift
if displayLink != nil || keyboardHeight == 0.0 {
  return
}
```

I've added this check, because I've attached KV observer before any
keyboard movement. The reason why I've added it in
`UIWindow.didBecomeVisibleNotification`/`UIWindow.didBecomeHiddenNotification`
was the fact, that these methods were called only one time (keyboard
events can be fired multiple times). But I've added `hasKVObserver`
variable in
#146
so it's safe to call `setupKVObserver`/`removeKVObserver` multiple
times.

So in this PR I've decided to stick to this approach - don't reset
`keyboardHeight` to `0` + setup KV listeners in different lifecycle
methods.

Should close
#175

## 📢 Changelog

### iOS
- moved `setupKVObserver`/`removeKVObserver` to
`keyboaardDidAppear`/`keyboardWilHide` lifecycle;
- don't set `keyboardHeight` to `0` (this value acts as
`persisteKeyboardHeight` on Android);

## 🤔 How Has This Been Tested?

Tested on:
- iPhone 6s (iOS 15.6);
- iPhone 14 Pro (iOS 16.2);
- iPhone 11 (iOS 16.5);

## 📸 Screenshots (if appropriate):

|Before|After|
|------|-----|
|<video
src="https://github.com/kirillzyusko/react-native-keyboard-controller/assets/22820318/82d46951-3471-4b59-8dd6-3062922a76f0">|<video
src="https://github.com/kirillzyusko/react-native-keyboard-controller/assets/22820318/b73d2aa2-72a9-4272-8b37-f6820d1c816a">|

## 📝 Checklist

- [x] CI successfully passed

Author: kirillzyusko

Diff for: ios/KeyboardMovementObserver.swift

@@ -65,26 +65,6 @@ public class KeyboardMovementObserver: NSObject {
       name: UIResponder.keyboardDidHideNotification,
       object: nil
     )
-    NotificationCenter.default.addObserver(
-      self,
-      selector: #selector(windowDidBecomeVisible),
-      name: UIWindow.didBecomeVisibleNotification,
-      object: nil
-    )
-    NotificationCenter.default.addObserver(
-      self,
-      selector: #selector(windowDidBecomeHidden),
-      name: UIWindow.didBecomeHiddenNotification,
-      object: nil
-    )
-  }
-
-  @objc func windowDidBecomeHidden(_: Notification) {
-    removeKVObserver()
-  }
-
-  @objc func windowDidBecomeVisible(_: Notification) {
-    setupKVObserver()
   }
 
   private func setupKVObserver() {
@@ -116,8 +96,8 @@ public class KeyboardMovementObserver: NSObject {
   ) {
     // swiftlint:disable:next force_cast
     if keyPath == "center", object as! NSObject == _keyboardView! {
-      // if we are currently animating keyboard or keyboard is not shown yet -> we need to ignore values from KVO
-      if displayLink != nil || keyboardHeight == 0.0 {
+      // if we are currently animating keyboard -> we need to ignore values from KVO
+      if displayLink != nil {
         return
       }
 
@@ -170,6 +150,7 @@ public class KeyboardMovementObserver: NSObject {
     onNotify("KeyboardController::keyboardWillHide", data)
 
     setupKeyboardWatcher()
+    removeKVObserver()
   }
 
   @objc func keyboardDidAppear(_ notification: Notification) {
@@ -184,15 +165,14 @@ public class KeyboardMovementObserver: NSObject {
       onNotify("KeyboardController::keyboardDidShow", data)
 
       removeKeyboardWatcher()
+      setupKVObserver()
     }
   }
 
   @objc func keyboardDidDisappear() {
     var data = [AnyHashable: Any]()
     data["height"] = 0
 
-    keyboardHeight = 0.0
-
     onEvent("onKeyboardMoveEnd", 0 as NSNumber, 0)
     onNotify("KeyboardController::keyboardDidHide", data)