[docs-infra] Remove codesandbox

[Janpot]

Remove stackblitz/codesandbox buttons and replace with a single "Open sandbox" button that opens StackBlitz with the demo/template.

• https://deploy-preview-47046--material-ui.netlify.app/material-ui/getting-started/templates/
• https://deploy-preview-47046--material-ui.netlify.app/material-ui/react-button/#basic-button
• https://deploy-preview-47046--material-ui.netlify.app/joy-ui/getting-started/templates/
• https://deploy-preview-47046--material-ui.netlify.app/joy-ui/customization/theme-builder/#color

Closes https://github.com/mui/mui-public/issues/723

Some benchmarks for the button/icon

Chakra Ariakit React HeroUI Ant design