How to use autocomplete paths with scss mixins ?

Hi,

Is it possible to use autocomplete paths to complete scss mixins variables ? Like:
```
@mixin backgroundImage($filename,$couleur:transparent,$position:top left,$repeat: no-repeat) {
background: $couleur url('#{$imagedir}#{$filename}') $position $repeat;
}
```

Thanks

No implementation files, tests, or entry points are named. Start by locating the repository's SCSS and path-completion handling, then review existing autocomplete tests; done would require a defined, tested behavior for completing paths in SCSS mixin variables.

Written by the indexing model from the issue text.