Add GTK4 versions of original Vala Wiki GTK Samples #21
Description
Focus on these: https://wiki.gnome.org/Projects/Vala/GTKSample
More can be added later on over time.
Samples to add:
- Minimal App Example
- Basic App Example
- Synchronizing Widgets
- Text File Viewer App
- ListView with GLib.ListStore
- ListView with CheckButtons
- ColumnView with GLib.ListStore
- Clipboard
- Entry completion with two cells