With qmake project user is able to add libraries by e.g. right clicking on the project -> "Add Library". This feature is disabled with cmake projects (greyed out in the context menu).
User should be able to add libraries to existing cmake projects and if the project has multiple targets, make selection which target should the library be added to.
Once the selection has been done something like this should be added / modified / appended to the CMakeList.txt:
target_link_libraries(some_target PRIVATE some_lib)