Add window position and size memory feature

[Vaso73]

Description

This feature remembers and restores the application window position, size, and state when the user closes and reopens vmPing.

Changes

• Added window position properties to ApplicationOptions class
• Created ApplicationSettings class to handle XML-based settings persistence
• Updated MainWindow.xaml.cs to load and save window position on startup and window state changes
• Window position is saved automatically when user moves, resizes, or changes window state

Files Changed

• vmPing/Classes/ApplicationOptions.cs
• vmPing/Classes/ApplicationSettings.cs
• vmPing/UI/MainWindow.xaml.cs

Testing

• Open vmPing
• Move and resize the window
• Close the application
• Reopen vmPing - window should be in the same position and size