Add a hello world project built with cmake

blink-cmake/.gitignore

blink-cmake/CMakeLists.txt

blink-cmake/README.md

blink-cmake/cmake/toolchain_arm-none-eabi.cmake

blink-cmake/main.c

blink-cmake/openocd.cfg

blink-cmake/samd51/CMSIS/Documentation/Core/html/index.html

blink-cmake/samd51/CMSIS/Include/arm_common_tables.h

blink-cmake/samd51/CMSIS/Include/arm_const_structs.h

blink-cmake/samd51/CMSIS/Include/arm_math.h

blink-cmake/samd51/CMSIS/Include/cmsis_armcc.h

blink-cmake/samd51/CMSIS/Include/cmsis_armclang.h

blink-cmake/samd51/CMSIS/Include/cmsis_compiler.h

blink-cmake/samd51/CMSIS/Include/cmsis_gcc.h

blink-cmake/samd51/CMSIS/Include/core_armv8mbl.h

blink-cmake/samd51/CMSIS/Include/core_armv8mml.h

blink-cmake/samd51/CMSIS/Include/core_cm0.h

blink-cmake/samd51/CMSIS/Include/core_cm0plus.h

blink-cmake/samd51/CMSIS/Include/core_cm23.h

blink-cmake/samd51/CMSIS/Include/core_cm3.h