Split CMake example and test targets into multiple `CMakeLists.txt`

CMakeLists.txt

miosix/_examples/asm/CMakeLists.txt

miosix/_examples/atsam4l_lcd/CMakeLists.txt

miosix/_examples/blinking_led/CMakeLists.txt

miosix/_examples/datalogger/CMakeLists.txt

miosix/_examples/deep_sleep/CMakeLists.txt

miosix/_examples/hd44780/CMakeLists.txt

miosix/_examples/ir_decoder/CMakeLists.txt

miosix/_examples/led_display/CMakeLists.txt

miosix/_examples/loop_mount/CMakeLists.txt

miosix/_examples/sad_trombone/CMakeLists.txt

miosix/_examples/servo/CMakeLists.txt

miosix/_examples/streamwriter/CMakeLists.txt

miosix/_examples/termios/CMakeLists.txt

miosix/_examples/thread_native/CMakeLists.txt

miosix/_examples/thread_pthread/CMakeLists.txt

miosix/_tools/delay_test/CMakeLists.txt

miosix/_tools/feedforward_profiling/board/CMakeLists.txt

miosix/_tools/feedforward_profiling/board/test1.cpp

miosix/_tools/feedforward_profiling/board/test2.cpp