[breaking] Consider dropping built-in integration with Express v4 and replacing it with Express v5 (or having no built-in integrations other than startStandaloneServer)
`@apollo/server` has express v4 as a dependency. After several years, express is moving forward with releasing v5 (currently published as `next` tag). Having support for v5 here would unblock and encourage people to upgrade.

https://www.npmjs.com/package/express?activeTab=versions
https://github.com/expressjs/express/releases/tag/v5.0.0

At this time, I have not checked for breaking changes in this repo, but wanted to open this issue to get things rolling. Any changes could be published under the `next` tag as well.