New C++20 bindings for lvgl 9.x

I think there still no C++ bindings for lvgl 9.x so I created this C++20 wrapper 
https://github.com/aptumfr/lv

Everything compiles with 2 demos working (ebike and smartwatch)
Please be free to share feedback about it and the design decisions.

I used C++20 because of many useful features and with zero-cost abstraction in mind.

