ng generate library virtusUI --style=scss gives an error

```
- [ ] bug report -> please search issues before submitting
- [x] feature request
```
It would be cool to generate library with SCSS system.
```
ng generate library virtusUI --style=scss
```
Now I'm getting an error
```
Schematic input does not validate against the Schema: {"style":"scss","entryFile":"public_api","prefix":"lib","skipPackageJson":false,"skipTsConfig":false}
Errors:

Data path "" should NOT have additional properties(style).
```

Start by reproducing `ng generate library virtusUI --style=scss` and inspect the library-generation schematic and its schema validation. The change is complete when the `style` option is accepted and the generated library uses SCSS without the additional-properties error.

Written by the indexing model from the issue text.