Port and renew CMake tutorial from Community to Develop
My biggest hurdle learning Qt/KDE Frameworks by far was CMake. Now that I know how to use it, I like it. I was planning on writing a tutorial from scratch, but apparently https://community.kde.org/Guidelines_and_HOWTOs/CMake exists.
We already have a Kirigami-oriented CMake tutorial on Develop, but I think a centralized tutorial that applies to all areas would be ideal. We could then link every single tutorial to it whenever we want to refer users to learn more about it, reducing the amount of technical explanations spread out throughout Develop.
As a bonus, this should allow us to explain what ECM actually provides and why/when it's worth using. Currently ECM information is too spread out in the tutorials, and the API website for it is very technical. Notable changes between Qt5 and Qt6 CMake API could be mentioned there as well.