[DataGrid] Allow to control the grid density

[MBilalShafi]

Resolves #5647

Changelog

Breaking changes

• The density is a controlled prop now, if you were previously passing the density prop to the Data Grid, you will need to do one of the following:

1. Move it to the initialState.density to initialize it.

   <DataGrid
   -  density="compact"
   +  initialState={{ density: "compact" }}
   />

2. Move it to the state and use onDensityChange callback to update the density prop accordingly for it to work as expected.

   + const [density, setDensity] = React.useState<GridDensity>('compact');
   <DataGrid
   -  density="compact"
   +  density={density}
   +  onDensityChange={(newDensity) => setDensity(newDensity)}
   />

• The selector gridDensityValueSelector was removed, use the gridDensitySelector instead.

[mui-bot]

Deploy preview: https://deploy-preview-12332--material-ui-x.netlify.app/

Updated pages:

• docs/data/data-grid/accessibility/accessibility.md
• docs/data/migration/migration-data-grid-v6/migration-data-grid-v6.md

Generated by 🚫 dangerJS against 72580e5

[github-actions]

This pull request has conflicts, please resolve those before we can evaluate the pull request.

[MBilalShafi]

Update: I may have to rework this to make it a proper controlled model