dump: check table key type for token_filters

In case of ``TABLE_NO_KEY``, ``grn_obj_get_info(ctx, table, GRN_INFO_TOKEN_FILTERS, &token_filters)`` outputs a following error message.

```
#|e| [info][get][token-filters] target object must be one of GRN_TABLE_HASH_KEY, GRN_TABLE_PAT_KEY and GRN_TABLE_DAT_KEY: 51
```