This moves the shell component into its own subsys and groups all
related files and options into a single place.
Additionally, one Kconfig option will now be required to enable the
shell:
CONFIG_CONSOLE_SHELL=y
The header files was also moved to include/shell/shell.h and can be now
referenced with
#include <shell/shell.h>
instead of
#include <misc/shell.h>
Updated documentation as well.
Change-Id: Iffbba4acfa05408055e9fd28dffa213451351f94
Signed-off-by: Anas Nashif <anas.nashif@intel.com>