Handle service name for scoped packages with archive white list specified

`package.json`:
```json
{
  "name": "@my-scope/my-package",
  "files": [
    "dist",
    "README.md"
  ],
...
}
```

```bash
./node_modules/.bin/speculate -n custom-name
Error: ENOENT: no such file or directory, lstat '/path/to/project/@my-scope/my-package.service'
```