Add window state save/restore feature

[Zakariathr22]

Description

• Adds support for saving and restoring main window size, position, scale, and maximized state between sessions.
• Introduces new settings properties and UI toggle for enabling/disabling this feature.
• Implements WindowStateHelper and WindowState classes for state management.
• Window state is restored on load and saved on close if enabled in Settings page.

Motivation and Context

• Closes Resize the window on startup #1606

How Has This Been Tested?

Manually tested

Screenshots (if appropriate):

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

[niels9001]

@Zakariathr22 I haven't tested this yet, will do soon! How will this work when moving between monitors? E.g. opening the app on multi-monitor setup, and then unplugging and only using the laptop's screen?

[Zakariathr22]

@Zakariathr22 I haven't tested this yet, will do soon! How will this work when moving between monitors? E.g. opening the app on multi-monitor setup, and then unplugging and only using the laptop's screen?

I tested it, and the window consistently reopens on the main screen after being closed and launched again.

How the code works:

• Retrieves the AppWindow instance.
• Uses XamlRoot.RasterizationScale to account for DPI scaling, ensuring the window maintains the same physical size across different monitors.
• Before saving the window state, it temporarily restores the window if it is maximized. This ensures the actual window size is saved rather than the maximized dimensions.
• When restoring the window state, it validates the saved position against the display area bounds to keep the window fully visible and prevent it from appearing partially off-screen or on a disconnected monitor.