Add a desktop-like about app page
Summary
Adds a page about the application, an About KDE activity and a simple easter egg. This MR tries to repeat the desktop About even with its internal architecture. It implements the AboutData class which is quite similar to KAboutData from KDE Frameworks.
Screenshots
When there is enough space, buttons are laid out horizontally (not in the grid)
(full screenshot)
Also on tablet
Video
Easter Egg
This MR also adds a simple Easter Egg similar to those found in Android (and why not add some fun to the app). It's easy to get into it: click on the top card with the application icon, description and version (but not the description) 3 times within 500 milliseconds. In Easter Egg, you can rotate the KDE logo by turning your device, and even change the logo to a random icon (or even Konqi) with a long press on the screen. Screenrecorder-2021-03-23-20-04-38-609