Fix quoting in ‘message_with_string’

Fix quoting in ‘message_with_string’

* src/nsfont.m (nsfont_open): Use directed quotes in format; they
should work now.
* src/xdisp.c (message_to_stderr): New function, refactored from
part of ‘message3_nolog’.
(message3_nolog): Use it.
(message_with_string): Use it.  Don’t mishandle NUL bytes when
noninteractive.  Prefer AUTO_STRING when it’s most likely faster.
Use ‘format-message’, not ‘format’, so that quotes are translated.