fix: memory leak on Android (#1343)

## 📜 Description

Improving memory leak behavior on Android.

## 💡 Motivation and Context

As described in
#1334
- it doesn't fully solves memory leaks when activity restarts, but it
resolves some other issues that could cause memory leak further.

There is no breaking changes, so it's safe to have these changes 🤞 

Partial fix without breaking changes for
#1334

## 📢 Changelog

<!-- High level overview of important changes -->
<!-- For example: fixed status bar manipulation; added new types
declarations; -->
<!-- If your changes don't affect one of platform/language below - then
remove this platform/language -->

### Android

- cleanup `layoutListener`;
- track `attachedContent`;
- cleanup `attachedContent`;
- remove listener that has been attached to `attachedContent`;

## 🤔 How Has This Been Tested?

Tested on Pixel 7 PRO (API 36).

## 📝 Checklist

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

Author: kirillzyusko

android/src/main/java/com/reactnativekeyboardcontroller/listeners/WindowDimensionListener.kt

@@ -18,13 +18,15 @@ class WindowDimensionListener(
 ) {
   private var lastDispatchedDimensions = Dimensions(0.0, 0.0)
   private var layoutListener: ViewTreeObserver.OnGlobalLayoutListener? = null
+  private var attachedContent: ViewGroup? = null
 
   public fun attachListener() {
     // attach to content view only once per app instance
     if (context != null && listenerID != context.hashCode()) {
       listenerID = context.hashCode()
 
       val content = context.content
+      attachedContent = content
 
       updateWindowDimensions(content)
 
@@ -38,7 +40,9 @@ class WindowDimensionListener(
   }
 
   public fun detachListener() {
-    context?.content?.viewTreeObserver?.removeOnGlobalLayoutListener(layoutListener)
+    attachedContent?.viewTreeObserver?.removeOnGlobalLayoutListener(layoutListener)
+    attachedContent = null
+    layoutListener = null
   }
 
   private fun updateWindowDimensions(content: ViewGroup?) {