Duplicate classes for <td> and <div> in table cells

Hi!

I have upgraded mui-datatables: 2.12.0 -> 3.7.8. I found some breaking changes messing up our layouts in a huge frontend application. The reason is the new inner div element that is now rendered inside the table cell, while also receiving the same classes as the conatining element from `setCellProps`. This is problematic for styles like padding and border, where paddings double up, and inner borders appear.

Layout after upgrading:

Layout when I remove the inner divs with the duplicate classes (with inspector):

## Expected Behavior

When rendering the table,
- there should be no inner div elements, as it was before. I could not find any reason in the history for this change.
- OR the divs should not receive the same classes as the td elements from `setCellProps`
- OR there should be a way to specify classes for the td and the inner div element

---
*EDIT*
## Current Behavior
I tried to reproduce the issue in the code sandbox. I have found out, that if I set the styles property with setCellProps, than the divs do not receive the styles, but when setting the className, both the div and the td element receive it.

```jsx
import React from "react";
import ReactDOM from "react-dom";
import MUIDataTable from "mui-datatables";

import makeStyles from '@material-ui/styles/makeStyles';

const myStyles = {
padding: 8,
border: '1px solid black'
};

const useStyles = makeStyles(() => ({
test: myStyles,
}))

function App() {
const classes = useStyles();
const columns = [{name: "Name", options: {
setCellProps: (_, index) => (index % 2 === 0 ? { style: myStyles } : { className: classes.test })
}}];

const options = {
filter: true,
filterType: "dropdown",
};

const data = [
["Gabby Georgee", "Business Analyst", "Minneapolis"],
[
"Aiden Lloyd",
"Business Consultant for an International Company and CEO of Tony's Burger Palace",
"Dallas"
],
["Jaden Collins", "Attorney", "Santa Ana"],
["Franky Rees", "Business Analyst", "St. Petersburg"],
["Aaren Rose", null, "Toledo"],
["Johnny Jones", "Business Analyst", "St. Petersburg"],
["Jimmy Johns", "Business Analyst", "Baltimore"],
["Jack Jackson", "Business Analyst", "El Paso"],
["Joe Jones", "Computer Programmer", "El Paso"],
["Jacky Jackson", "Business Consultant", "Baltimore"],
["Jo Jo", "Software Developer", "Washington DC"],
["Donna Marie", "Business Manager", "Annapolis"]
];

return (



);
}

ReactDOM.render(, document.getElementById("root"));
```
Top highlight:
`setCellProps: (_, index) => (index % 2 === 0 ? { style: myStyles } : { className: classes.test })`

*EDIT 2*
Removing lines https://github.com/gregnb/mui-datatables/blob/master/src/components/TableBodyCell.js#L146 https://github.com/gregnb/mui-datatables/blob/master/src/components/TableBodyCell.js#L167 solves the problem, I have checked in a code sandbox.
## Your Environment

| Tech | Version |
|--------------|---------|
| Material-UI | 4.11 |
| MUI-datatables | 3.7.8 |
| React | 16.8 |
| browser | chrome |

Start in src/components/TableBodyCell.js at the referenced lines 146 and 167, then reproduce the issue with the provided setCellProps example in a code sandbox. Verify how className and style are applied to the td and inner div. Done means class-based cell props no longer create the reported duplicate layout effects, with the existing behavior preserved for styles.

Written by the indexing model from the issue text.