VERSION: move COPYRIGHT_STARTUP_MESSAGE as SAMBA_COPYRIGHT_STRING into version.h

VERSION: move COPYRIGHT_STARTUP_MESSAGE as SAMBA_COPYRIGHT_STRING into version.h

We also prodive a samba_copyright_string() helper similar to
samba_version_string().

BUG: https://bugzilla.samba.org/show_bug.cgi?id=15377

Signed-off-by: Stefan Metzmacher <metze@samba.org>
Reviewed-by: Björn Jacke <bjacke@samba.org>
Reviewed-by: Andrew Bartlett <abartlet@samba.org>
Autobuild-User(master): Stefan Metzmacher <metze@samba.org>
Autobuild-Date(master): Fri Dec 15 10:44:42 UTC 2023 on atb-devel-224

(cherry picked from commit d23d6145bf08c4765479951237e697c4b2b11aa2)

Autobuild-User(v4-19-test): Jule Anger <janger@samba.org>
Autobuild-Date(v4-19-test): Tue Dec 19 10:43:21 UTC 2023 on atb-devel-224