Allow excluding attached names via `!`

### Please describe your feature request

Enable the following syntax:

```r
box::use(stats[..., ! filter])
```

To import and attach all names from the ‘stats’ package, except the name `filter`. This comes in handy to avoid name conflicts between two attached packages (e.g. `stats::filter` and `dplyr::filter`) and makes order of import declarations less important.

Ensure that `!` declarations are only valid in conjunction with `...` wildcard declarations (since they are otherwise meaningless).

Start by tracing how box::use parses wildcard declarations and attaches names, using the shown stats[..., ! filter] syntax as the entry point. Ensure exclusions are accepted only alongside ..., and verify that filter is omitted while other stats names remain attached.

Written by the indexing model from the issue text.