Add locked narrowing around pre- and post-command-hook

Add locked narrowing around pre- and post-command-hook

* src/keyboard.c (safe_run_hooks_maybe_narrowed): New function.
(command_loop_1): Use it for 'pre-command-hook' and 'post-command-hook'.
(syms_of_keyboard): Update docstrings of 'pre-command-hook' and
'post-command-hook'.

* src/lisp.h: Prototype of the new function.