MLECO-6488: Add test coverage provision in build to LLM module
- Add code coverage for C++ layer
- New cmake utility to enable code coverage flags for GCC compiler
- Use cmake_dependent_option for ability to set ENABLE_COVERAGE only for Debug builds
Signed-off-by: Fernando Barreto Rodrigues fernando.barretorodrigues@arm.com Change-Id: I1c3c1c73089662ec2e577f7c7b3b2f7c8810993f