Code snippet tool

[rabbitism]

Add a toolkit for generating Avalonia related code snippets.

1. Instead of manipulating code snippets inside option window, just add a link in option to open a window.
2. User can customize what code snippets to include, what the short cuts for selected snippets to export.
3. User guidance of importing code snippets in visual studio.

[rabbitism]

Default Code Snippets.

Avalonia General

• [ ] Styled Property
• [ ] ReadOnly StyledProperty
• [ ] Direct Property
• [ ] Attached Property

View Model specific

• [ ] RaisePropertyChange property (Prism)
• [ ] OnPropertyChange property (INotifyPropertyChanged)
• [ ] RaiseAndSetIfChanged property (ReactiveUI)
• [ ] DelegateCommand (Prism)
• [ ] ReactiveCommand (ReactiveUI)