Due to my lack of knowledge of CMake and C++ in general, I had to do the following:
configure_file(${CMAKE_CURRENT_SOURCE_DIR}/resources/vindec_resource_countries.txt
${CMAKE_BINARY_DIR} COPYONLY)
configure_file(${CMAKE_CURRENT_SOURCE_DIR}/resources/vindec_resource_manufacturers.txt
${CMAKE_BINARY_DIR} COPYONLY)
This means that the resource files are output to the root build directory:

I access the files like this because I don't know how to access them if they were inside a subdirectory rather than the root build directory.
std::string getManufaturer(const char *manufacturerCode) {
return getValue(manufacturerCode, "vindec_resource_manufacturers.txt");
}
I would really love some assistance on this!