fix: hide OverKeyboardView on app reload (#638)

## 📜 Description

Hide `OverKeyboardView` when app gets reload from Dev menu.

## 💡 Motivation and Context

I tested Android and iOS Fabric and didn't notice that issue. For me it
seems like it's specific to iOS paper architecture. Initially I thought
that it's because of memory leaks and that component can not be
unmounted - but I haunted memory leaks and XCode profiler didn't show up
any memory leaks 🤷‍♂️ (I also removed big parts of the code but still
could see "zombie" views).

To fix the problem I decided to add listener for
`RCTJavaScriptWillStartLoadingNotification` event and call `hide`. I
tested and it works well, so let's keep this code for now 😊

Closes
#637

## 📢 Changelog

### iOS

- add `RCTJavaScriptWillStartLoadingNotification` listener in
`OverKeyboardView` constructor with `hide` selector;
- clear listener in `dealloc`;

## 🤔 How Has This Been Tested?

Tested manually on iPhone 15 Pro.

## 📸 Screenshots (if appropriate):

|Before|After|
|-------|-----|
|<video
src="https://github.com/user-attachments/assets/c069277a-74b4-4b4a-91ad-12a852f89abb">|<video
src="https://github.com/user-attachments/assets/e94240bf-ddac-4e97-97ab-faa5f262c5e1">|

## 📝 Checklist

- [x] CI successfully passed
- [x] I added new mocks and corresponding unit-tests if library API was
changed

ios/views/OverKeyboardViewManager.mm

@@ -102,10 +102,19 @@ - (instancetype)initWithBridge:(RCTBridge *)bridge
     _touchHandler = [[RCTTouchHandler alloc] initWithBridge:bridge];
     _contentView = [[UIView alloc] initWithFrame:CGRectZero];
   }
+  [[NSNotificationCenter defaultCenter] addObserver:self
+                                           selector:@selector(hide)
+                                               name:RCTJavaScriptWillStartLoadingNotification
+                                             object:nil];
   return self;
 }
 #endif
 
+- (void)dealloc
+{
+  [[NSNotificationCenter defaultCenter] removeObserver:self];
+}
+
 // MARK: lifecycle methods
 - (void)didMoveToSuperview
 {