Export validation rules 

Right now user always need to create validation rules manully.

The goal is to have validation rules fabric funcitons. For example:

```js
import { max, required } from 'vuestic-ui/validation-rules'
```

```html
<VaInput :rules="[required(), max(6)]" />
```

We need a separate build config, look at packages/ui/build.

Subtask of https://github.com/epicmaxco/vuestic-ui/issues/4194