libnm: make NMSettingOvsExternalIDs.verify() deterministic

Iterating over a hash table is not deterministic. When we have
two invalid keys in ovs-external-ids, we should deterministically
get the same error message.

Instead, iterate over the (sorted) keys. This does have an overhead,
because we need to fetch the keys, and we need to lookup each value
by key. Still, correctness and determinism is more important.

src/libnm-core-impl/nm-setting-ovs-external-ids.c

@@ -293,12 +293,16 @@ verify(NMSetting *setting, NMConnection *connection, GError **error)
 
     if (priv->data) {
         gs_free_error GError *local = NULL;
-        GHashTableIter        iter;
+        const char *const    *keys;
-        const char           *key;
+        guint                 len;
-        const char           *val;
+        guint                 i;
+
+        keys = nm_setting_ovs_external_ids_get_data_keys(self, &len);
+
+        for (i = 0; i < len; i++) {
+            const char *key = keys[i];
+            const char *val = g_hash_table_lookup(priv->data, key);
 
-        g_hash_table_iter_init(&iter, priv->data);
-        while (g_hash_table_iter_next(&iter, (gpointer *) &key, (gpointer *) &val)) {
             if (!nm_setting_ovs_external_ids_check_key(key, &local)) {
                 g_set_error(error,
                             NM_CONNECTION_ERROR,