linting: Check sample loc files exist under tool-data/

Check `tool-data/example.loc.sample` is included if used in a tool's `` tag.

This should look for both the old style, e.g.:

```

```

and the new style, e.g.

```



```

where the name of the location file to check is in the matching XML file `tool-data/tool_data_table_conf.xml.sample`:

```
value, name, path



```