Support C++20 modules.

Update `drogon_ctl` to create C++20 modules. Seeing that Drogon now supports C++20, can we get an option that asks what kind of Controller, Filter, or View file we prefer? C++20 modules will be awesome seeing that CMake now supports it out of the box with GCC*14*. This is just my opinion, I know it won’t be easy but if it is in a queue and there is an ETA, then we will stay optimistic and give our contribution no matter how little.