cmake OpenVINOGenAI examples

openvinotoolkit/openvino.genai samples/c/text_generation/CMakeLists.txt :4

find_package(OpenVINOGenAI REQUIRED
    PATHS
        "${CMAKE_BINARY_DIR}"  # Reuse the package from the build.
        ${OpenVINO_DIR}  # GenAI may be installed alogside OpenVINO.
    NO_CMAKE_FIND_ROOT_PATH
)