Expose top-level for all cpp code
This is required since sqlite_orm is required by some CommonCpp projects
This is part of a larger effort to bring more structure to the C++ codebase https://linear.app/comm/issue/ENG-1310/export-nativecpp-projects-as-cmake-projects
The intent is to be able to reference the dependencies as packages, instead of just as GLOB'ing over certain directories; which is a major anti-pattern in CMake as it create a bunch of footguns such as finding multiple files with `main()` defined, or picking up unrelated code in generated folders.