checkpatch: Check for strcpy and strncpy too

Warn about strcpy(), strncpy(), and strlcpy(). Suggest strscpy() and
include pointers to the open KSPP issues for each, which has further
details and replacement procedures.

Cc: Andy Whitcroft <apw@canonical.com>
Cc: Joe Perches <joe@perches.com>
Cc: Dwaipayan Ray <dwaipayanray1@gmail.com>
Cc: Lukas Bulwahn <lukas.bulwahn@gmail.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20230517201349.never.582-kees@kernel.org