1. Created new shell module: shell_help.
2. Simplified command handlers with new shell print macros.
3. Removed help functions from command handlers.
Signed-off-by: Jakub Rzeszutko <jakub.rzeszutko@nordicsemi.no>
Removing help "options" from shell API.
Currently SHELL_OPT macro is not used by users. What is more
commit: a89690d10f ignores possible options created in
command handler by the user. As a result they are not printed
in help message.
Second, currntly implemented "options" in command handlers options are
implemented without SHELL_OPT macro.
And last but not least this change will allow to implement
help handler in a way that user will not need to think about calling
functions printing help in a command handler.
Signed-off-by: Jakub Rzeszutko <jakub.rzeszutko@nordicsemi.no>
1. Command handler can return command exectution status as int.
2. Existing command handlers rework.
Signed-off-by: Jakub Rzeszutko <jakub.rzeszutko@nordicsemi.no>
