[website] switch between esm and cjs examples

Many examples are CJS only, it would be neat if we had a switch component where you can show examples either in cjs or esm. https://www.graphql-tools.com/docs/documents-loading

Start with the linked documents-loading page and inspect how its examples are authored and rendered. Determine where a CJS/ESM switch could apply across the examples; done means readers can switch between both module styles and see the corresponding code consistently.

Written by the indexing model from the issue text.