kdc: refactor Samba-specific auditing API in terms of existing API

Make Samba-specific HDB auth status API a wrapper on the existing auditing API,
with a view towards unifying the two APIs in a future commit.

The term "auth status" is replaced with "auth event", and the HDB auth_status
method is replaced with a more general purpose audit method which has access to
the entire request structure.

kdc/version-script.map

@@ -21,6 +21,9 @@ HEIMDAL_KDC_1.0 {
 		krb5_kdc_update_time;
 		krb5_kdc_pk_initialize;
 		_kdc_audit_addkv;
+		_kdc_audit_addkv_object;
+		_kdc_audit_delkv;
+		_kdc_audit_getkv;
 		_kdc_audit_addreason;
 		_kdc_audit_vaddkv;
 		_kdc_audit_vaddreason;