CVE-2022-2031 s4:kpasswd: Return a kpasswd error code in KRB-ERROR

CVE-2022-2031 s4:kpasswd: Return a kpasswd error code in KRB-ERROR

If we attempt to return an error code outside of Heimdal's allowed range
[KRB5KDC_ERR_NONE, KRB5_ERR_RCSID), it will be replaced with a GENERIC
error, and the error text will be set to the meaningless result of
krb5_get_error_message(). Avoid this by ensuring the error code is in
the correct range.

BUG: https://bugzilla.samba.org/show_bug.cgi?id=15047
BUG: https://bugzilla.samba.org/show_bug.cgi?id=15049
BUG: https://bugzilla.samba.org/show_bug.cgi?id=15074

Signed-off-by: Joseph Sutton <josephsutton@catalyst.net.nz>
Reviewed-by: Andreas Schneider <asn@samba.org>