Add unimplemented styles

In order to avoid QtQuick Controls complain for missing styles when using
Minimalist, we provide unimplemented styles.
Group box style

Implement group box style.
ToolBar style

Style for toolbars with noise texture.
TabView style initial version

TabView style, still Work in progress.
Improved ProgressBar style

Not yet finished, but it's better than before.
Less subtle gradient for TextField style

Improve gradient a little bit.
Add new styles to the project

Add the new files to the project.