Rewrite arm11_handle_bool to provide a generic on/off command helper.

Refactors COMMAND_PARSE_BOOL to use new command_parse_bool helper,
which gets reused by the new command_parse_bool_any helper.
This later helper is called by the new command helper function to
accepts any on/off, enable/disable, true/false, yes/no, or 0/1 parameter.