App onbarding for new users with interactive click overlays

[joergreichert]

Current state: There is no direct onboarding for new LeipzigGiesst users.

Motivation: To get known to the most common features of the app and the way / process to use it there should be a step to step tutorial directly built in within the app using hot spots / tooltips, clf. https://userguiding.com/blog/react-onboarding-tour/

Future state: At first login there is an click by click tour how to adopt and water your first tree, which can be skipped of course.