Deduplicate code from various packages into "react-router"

[ryanflorence]

• PR Move server-runtime into react-router #11698
• Followup PR to remove re-exports: no react-router re-exports from node #11702

Pedro had started working on this task to move all shared things into the "remix" package, now it all goes to "react-router"

[markdalgleish]

I've started looking into this as part of moving the runtime/adapter packages out of the monorepo since it means we likely don't want to re-export the entire server-runtime API from these standalone packages anymore.