[data grid] Add a default background color to the data grid

[KenanYusuf]

See the following issues:

• https://github.com/mui/mui-x/issues/13549
• https://github.com/mui/mui-x/issues/5979

• 15502

I propose that in v8, we set a default background color on the data grid to avoid such issues.

We could make it customizable through the theme mixin:

import { createTheme } from '@mui/material/styles';
import type {} from '@mui/x-data-grid/themeAugmentation';

const theme = createTheme({
  mixins: {
    MuiDataGrid: {
+     background: '#340606',
      pinnedBackground: '#340606',
      containerBackground: '#343434',
    },
  },
});

[michelengelen]

added one more issue