Summary:
I'm adding the `.deb` option to linux build, it makes easier to install.
```bash
cd desktop
yarn build --linux --linux-deb
```
## Changelog
- Add deb target to linux build
Pull Request resolved: https://github.com/facebook/flipper/pull/1093
Reviewed By: mweststrate
Differential Revision: D21378807
Pulled By: passy
fbshipit-source-id: a72a85705d3c464cddd80091d38c92012bdbee2c