[Android] Fix NavigationBar overlapping StatusBar when NavigationBar visibility changes (#33359)

<!-- Please let the below note in for people that find this PR -->
> [!NOTE]
> Are you waiting for the changes in this PR to be merged?
> It would be very helpful if you could [test the resulting
artifacts](https://github.com/dotnet/maui/wiki/Testing-PR-Builds) from
this PR and let us know in a comment if this change resolves your issue.
Thank you!

### Issue Details
On Android, the content area in a TabbedPage shows incorrect layout when
tabs use mixed HasNavigationBar values (some true, some false). When
switching to a tab where the NavigationBar is visible, the content area
does not properly account for the toolbar height, resulting in content
being obscured by the NavigationBar.

**Regression PR:** #27294

### Root Cause
PR #27294 introduced a default
OffscreenPageLimit value, which pre-creates tab fragments during
initialization. When switching between tabs with different
HasNavigationBar values, Android's insets system does not automatically
recalculate layout measurements because they were cached during the
pre-creation phase. While the toolbar height updates correctly via
LayoutParameters, the content area continues using stale inset
measurements.

### Description of Change
Added a call to
AndroidX.Core.View.ViewCompat.RequestApplyInsets(nativeToolbar) in
ToolbarExtensions.UpdateIsVisible after updating LayoutParameters. This
explicitly requests Android to re-dispatch window insets through the
view hierarchy, triggering remeasurement of the content area when the
toolbar visibility or height changes.

**References:**

[Android/ContentViewGroup.cs#L149](https://github.com/dotnet/maui/blob/main/src/Core/src/Platform/Android/ContentViewGroup.cs#L149)

[Android/LayoutViewGroup.cs#L166](https://github.com/dotnet/maui/blob/main/src/Core/src/Platform/Android/LayoutViewGroup.cs#L166)

[Android/MauiScrollView.cs#L303](https://github.com/dotnet/maui/blob/main/src/Core/src/Platform/Android/MauiScrollView.cs#L303)

### Tested the behavior in the following platforms
 
- [x] Android
- [x] Windows
- [x] iOS
- [x] Mac

### Issues Fixed

Fixes #33340

### Screenshots

| Before Issue Fix | After Issue Fix |
|----------|----------|
| <video width="300" height="600"
src="https://github.com/user-attachments/assets/e15fe58b-a609-442c-911f-0e0f04ee8545">
| <video width="300" height="600"
src="https://github.com/user-attachments/assets/e5da01a3-c0b8-4fc1-a443-efff1409dd82">)
|

---------

Co-authored-by: Shane Neuville <[email protected]>
Co-authored-by: Jakub Florkowski <[email protected]>

Author: 3 people

src/Controls/src/Core/Platform/Android/Extensions/ToolbarExtensions.cs

@@ -47,6 +47,7 @@ public static void UpdateIsVisible(this AToolbar nativeToolbar, Toolbar toolbar)
 			}
 
 			nativeToolbar.LayoutParameters = lp;
+			AndroidX.Core.View.ViewCompat.RequestApplyInsets(nativeToolbar);
 		}
 
 		public static void UpdateTitleIcon(this AToolbar nativeToolbar, Toolbar toolbar)

src/Controls/tests/TestCases.Android.Tests/snapshots/android/NavigationBarLayoutWithMixedHasNavigationBar.png

@@ -0,0 +1,31 @@
+using Microsoft.Maui.Controls.PlatformConfiguration.AndroidSpecific;
+using TabbedPage = Microsoft.Maui.Controls.TabbedPage;
+
+namespace Maui.Controls.Sample.Issues;
+
+[Issue(IssueTracker.Github, 33340, "NavigationBar overlaps StatusBar in TabbedPage", PlatformAffected.Android)]
+public class Issue33340 : TabbedPage
+{
+    public Issue33340()
+    {
+        this.On<Microsoft.Maui.Controls.PlatformConfiguration.Android>().SetToolbarPlacement(ToolbarPlacement.Bottom);
+        var page1 = new ContentPage { Title = "Page1", Content = new Label { Text = "Page 1" } };
+        NavigationPage.SetHasNavigationBar(page1, false);
+        Children.Add(new NavigationPage(page1) { Title = "Tab1" });
+
+        var page2 = new ContentPage { Title = "Page2", Content = new Label { Text = "Page 2" } };
+        NavigationPage.SetHasNavigationBar(page2, false);
+        Children.Add(new NavigationPage(page2) { Title = "Tab2" });
+
+        var page3 = new ContentPage { Title = "Page3", Content = new Label { Text = "Page 3" } };
+        NavigationPage.SetHasNavigationBar(page3, false);
+        Children.Add(new NavigationPage(page3) { Title = "Tab3" });
+
+        var page4 = new ContentPage { Title = "Page4", Content = new Label { Text = "Page 4 with NavigationBar" } };
+        NavigationPage.SetHasNavigationBar(page4, true);
+        Children.Add(new NavigationPage(page4) { Title = "Tab4" });
+
+        CurrentPage = Children[0];
+    }
+}
+

src/Controls/tests/TestCases.HostApp/Issues/Issue33340.cs

@@ -0,0 +1,23 @@
+using NUnit.Framework;
+using UITest.Appium;
+using UITest.Core;
+
+namespace Microsoft.Maui.TestCases.Tests.Issues;
+
+public class Issue33340 : _IssuesUITest
+{
+    public Issue33340(TestDevice testDevice) : base(testDevice)
+    {
+    }
+
+    public override string Issue => "NavigationBar overlaps StatusBar in TabbedPage";
+
+    [Test]
+    [Category(UITestCategories.TabbedPage)]
+    public void NavigationBarLayoutWithMixedHasNavigationBar()
+    {
+        App.WaitForElement("Tab4");
+        App.Tap("Tab4");
+        VerifyScreenshot();
+    }
+}