Rename csv_process target to csv_process-lib and gate demo executable
- Rename library target from "csv_process" to "csv_process-lib"
- Add LIB_DEMO_ENABLE option (default OFF) to conditionally build the demo executable
- Drop -O2 compile/link options link dependency from the library target, and remove LINKER_LANGUAGE C override
- Changed cmake_modules GIT_TAG to "da9010833db7c4d06328fd6fb5840c998607c4d4"
- Remove redundant enable_language(C CXX) call and unused/commented-out lines