fix an issue where nav bar would stay visible together with the keyboard when NTP was opened (#6086)

Task/Issue URL:
https://app.asana.com/1/137249556945/project/1208671518894266/task/1210267290350843?focus=true

### Description
When opening the new tab page, we initial don't show the keyboard. This
scheduled a delayed task to execute and show the navigation bar. Before
the time elapses to run the task, we automatically show the keyboard and
focus on the omnibar, which hides the nav bar. However, the initially
scheduled task would eventually execute and re-show the navigation bar
even though the keyboard was also already visible.

The fix is to cancel the delayed task to show the navigation bar
whenever the keyboard state changes.

### Steps to test this PR

- [ ] Enable visual design experiment.
- [ ] Go to any page.
- [ ] Open a new tab page.
- [ ] Verify keyboard is visible and navigation bar isn't.
- [ ] Close the app and reopen it.
- [ ] Verify that when NTP loads, keyboard is visible and navigation bar
isn't.
- [ ] Try it multiple times.

Author: LukasPaczos

app/src/main/java/com/duckduckgo/app/browser/navigation/bar/BrowserNavigationBarViewIntegration.kt

@@ -29,6 +29,7 @@ import com.duckduckgo.common.ui.view.show
 import com.duckduckgo.common.utils.keyboardVisibilityFlow
 import kotlinx.coroutines.CoroutineScope
 import kotlinx.coroutines.Job
+import kotlinx.coroutines.delay
 import kotlinx.coroutines.flow.distinctUntilChanged
 import kotlinx.coroutines.launch
 
@@ -53,7 +54,8 @@ class BrowserNavigationBarViewIntegration(
     } ?: browserTabFragmentBinding.navigationBar
 
     private var stateObserverJob: Job? = null
-    private var keyboardVisibilityJob: Job? = null
+    private var keyboardVisibilityObserverJob: Job? = null
+    private var navigationBarVisibilityChangeJob: Job? = null
 
     init {
         stateObserverJob = lifecycleScope.launch {
@@ -92,21 +94,22 @@ class BrowserNavigationBarViewIntegration(
     private fun onEnabled() {
         // we're hiding the navigation bar when keyboard is shown,
         // to prevent it from being "pushed up" within the coordinator layout
-        keyboardVisibilityJob = lifecycleScope.launch {
+        keyboardVisibilityObserverJob = lifecycleScope.launch {
             omnibar.textInputRootView.keyboardVisibilityFlow().distinctUntilChanged().collect { keyboardVisible ->
+                navigationBarVisibilityChangeJob?.cancel()
                 if (keyboardVisible) {
                     navigationBarView.gone()
                 } else {
-                    navigationBarView.postDelayed(
-                        { navigationBarView.show() },
-                        BrowserTabFragment.KEYBOARD_DELAY,
-                    )
+                    navigationBarVisibilityChangeJob = launch {
+                        delay(BrowserTabFragment.KEYBOARD_DELAY)
+                        navigationBarView.show()
+                    }
                 }
             }
         }
     }
 
     private fun onDisabled() {
-        keyboardVisibilityJob?.cancel()
+        keyboardVisibilityObserverJob?.cancel()
     }
 }