[StatusBar][Android] Added StatusBarHandler to have control over statusbar in pages.

[Vetle444]

Added StatusBarHandler to provide per-page control over Android status bar appearance, with support for both modal and non-modal pages.

Problem

Previously, status bar color and icon style were set globally across the entire app. When navigating between pages with different backgrounds (e.g., a photo capture page with transparent status bar, then a regular page with colored background), the status bar couldn't adapt automatically. This was especially problematic in modal navigation scenarios.

Solution

Introduced two new properties on ContentPage:

• StatusBarColor: Sets the status bar background color for each page
• StatusBarStyle: Controls icon color (Clock, battery, etc.)
  • Auto - Automatically determines light/dark icons based on background luminosity (default)
  • Light - Light icons for dark backgrounds
  • Dark - Dark icons for light backgrounds

The StatusBarHandler automatically detects modal vs non-modal pages and applies the correct implementation:

• Non-modal pages: Sets color on Activity window
• Modal pages: Tracks DialogFragment-to-ContentPage mapping and sets color on dialog window

Status bar updates dynamically in OnAppearing(), ensuring correct appearance as users navigate.

Platform Differences

Android only - iOS status bar is controlled differently through Info.plist and native APIs.

Files Changed

• Added StatusBarHandler.cs - Core status bar management logic
• Modified FragmentLifeCycleCallback.cs - Registers/unregisters DialogFragment mappings
• Modified ContentPage.cs - Calls StatusBarHandler.TrySetStatusBarColor() in OnAppearing()
• Modified ContentPage.Properties.cs - Added StatusBarColor and StatusBarStyle properties

Usage Example

<dui:ContentPage StatusBarColor="Transparent"
                 StatusBarStyle="Light"
                 Background="Black">
    <!-- Content -->
</dui:ContentPage>