add simple posix tests to SITL

Makefile

cmake/configs/posix_sitl_default.cmake

posix-configs/SITL/init/test/cmd_template.in

posix-configs/SITL/init/test/tests_template.in

src/firmware/posix/sitl_tests.cmake

src/platforms/posix/tests/hello/hello_start_posix.cpp

src/platforms/posix/tests/hrt_test/CMakeLists.txt

src/platforms/posix/tests/hrt_test/hrt_test.cpp

src/platforms/posix/tests/hrt_test/hrt_test_start_posix.cpp

src/platforms/posix/tests/muorb/muorb_test_example.cpp

src/platforms/posix/tests/vcdev_test/CMakeLists.txt

src/platforms/posix/tests/vcdev_test/vcdevtest_example.cpp

...latforms/posix/tests/vcdev_test/vcdevtest_start_posix.cpp

src/platforms/posix/tests/wqueue/wqueue_start_posix.cpp

src/systemcmds/tests/tests_main.c