Split the `kernel_service.c` into multiple subcommand files,
each file would register with the main `kernel` cmd based on
the dependencies in Kconfig/CMakeLists.txt.
This greatly reduces the number of precompiler directives.
Signed-off-by: Yong Cong Sin <ycsin@meta.com>
Signed-off-by: Yong Cong Sin <yongcong.sin@gmail.com>
