move nuttx-configs to platforms/nuttx

platforms/nuttx/NuttX/CMakeLists.txt

platforms/nuttx/NuttX/tools/new_nuttx_px_config.sh

platforms/nuttx/cmake/px4_impl_os.cmake

platforms/nuttx/nuttx-configs/PX4_Config.mk

platforms/nuttx/nuttx-configs/PX4_Warnings.mk

platforms/nuttx/nuttx-configs/aerocore2/Kconfig

platforms/nuttx/nuttx-configs/aerocore2/include/board.h

...orms/nuttx/nuttx-configs/aerocore2/include/nsh_romfsimg.h

platforms/nuttx/nuttx-configs/aerocore2/nsh/Make.defs

platforms/nuttx/nuttx-configs/aerocore2/nsh/defconfig

platforms/nuttx/nuttx-configs/aerocore2/scripts/ld.script

platforms/nuttx/nuttx-configs/aerocore2/src/Makefile

platforms/nuttx/nuttx-configs/aerocore2/src/empty.c

platforms/nuttx/nuttx-configs/aerofc-v1/Kconfig

platforms/nuttx/nuttx-configs/aerofc-v1/include/board.h

...orms/nuttx/nuttx-configs/aerofc-v1/include/nsh_romfsimg.h

platforms/nuttx/nuttx-configs/aerofc-v1/nsh/Make.defs

platforms/nuttx/nuttx-configs/aerofc-v1/nsh/defconfig

platforms/nuttx/nuttx-configs/aerofc-v1/scripts/ld.script

platforms/nuttx/nuttx-configs/aerofc-v1/src/Makefile