macOS light and dark themes

[DevCharly]

This PR adds macOS light and dark themes that use macOS Monterey (v12.2) colors and style.

The intention was to create themes that look similar to native macOS applications.

The popup of not editable combo boxes is positioned similar to native macOS NSPopUpButton controls:

Known issues:

• changing accent color not yet supported
• tabbed pane style not macOS like
• selection in lists, tables, trees and menu items do not have round corners

To try it out, download the build artifacts from here: https://github.com/JFormDesigner/FlatLaf/actions/runs/2319472414

The new look and feel class names are:

• com.formdev.flatlaf.themes.FlatMacLightLaf
• com.formdev.flatlaf.themes.FlatMacDarkLaf