Support customing the fill attribute of the chart component

- [ ] I have searched the [issues](https://github.com/antvis/f2/issues) of this repository and believe that this is not a duplicate.

### What problem does this feature solve?
1. Help users more flexibly modify the background of the Chart component.
2. When I adapt to the company's hybrid container, will get some error when useing 'transparent'.

### What does the proposed API look like?
```
const { fillStyle } = props;

...

```

Locate the Chart component and inspect how its group style currently sets the fill, then compare it with the proposed fillStyle prop and transparent fallback. Confirm the component accepts a custom fill value without the hybrid-container error and verify the chart background remains unchanged by default.

Written by the indexing model from the issue text.