Resolvers naming convention for scoped packages

Hi!, thanks for this library, it's super useful.
I just published [@5rabbits/eslint-import-resolver-directory-named](https://www.npmjs.com/package/@5rabbits/eslint-import-resolver-directory-named) and It would be great if scoped packages follows the `eslint-import-resolver-*` convention), so that users can include it like this:

```yaml
settings:
import/resolver: @5rabbits/directory-named
```

Currently I'm using the full package name `import/resolver: @5rabbits/eslint-import-resolver-directory-named`, but it's kinda verbose 😞.

Start by tracing how resolver names are expanded and how scoped package names are handled. Add support for the shorter scoped form shown in the issue while preserving existing unscoped and full-name behavior, then run the relevant resolver tests; done means @5rabbits/directory-named resolves the published package.

Written by the indexing model from the issue text.