arq: multiple input files without repeating --data

### Version

4.8.0

### Feature

When executing queries with `arq` it is possible to provide multiple input files by repeating the `--data` option

This is a not shell-friendly, where I would like to glob a path to load multiple sources in one go

```
arq --query test.rq --data data/*.ttl
```

To make that work, it would be necessary to allow multiple values of `--data`

```
arq --query test.rq --data data/1.ttl data/2.ttl data/3.ttl
```

Can this be implemented?

### Are you interested in contributing a solution yourself?

None

Start at the arq command-line entry point and trace how the --data argument is parsed and passed to query execution. Check the existing repeated --data behavior, then verify that one --data option accepts multiple paths such as data/1.ttl data/2.ttl data/3.ttl and loads them all.

Written by the indexing model from the issue text.