Part 8: update Apollo Client imports (ApolloProvider, useQuery, useMutation) and setup to v4

[goncalooliveirasilva]

This PR updates Part 8 documentation to align with Apollo Client v4.

• Import ApolloProvider, useQuery, and useMutation from @apollo/client/react
• Replace direct uri shortcut with link: new HttpLink({ uri }) (required in Apollo Client v4)
• Improved one sentence for clarity in the setup instructions
• Applied changes consistently across all relevant Part 8 files, including translations
• Replace @apollo/server/express4 with @as-integrations/express (Express 5)
• Replace useServer import path from graphql-ws/lib/use/ws to graphql-ws/use/ws

These updates match the current Apollo docs and prevent runtime errors in React 18 + Vite setups.

Note: I noticed another open PR that updates Apollo Client imports, but only in one file.
This PR applies the updates consistently across all relevant Part 8 files (including translations), also updates useMutation imports, and improves one sentence for clarity.