chore: use single export

[jimmywarting]

I'm going to try and group export and put them at the bottom last and also using explicit path (with extension) cuz this really makes it much more easier to refactor the code into ESM at a later stage.

It's much more easier to see what things gets exported when they are put last as a group

Checklist

• I have ensured my pull request is not behind the beta branch of the original repository.
• I have rebased all commits where necessary so that reviewing this pull request can be done without having to merge it first.
• I have written a commit message that passes commitlint linting.
• I have ensured that my code changes pass linting tests.
• I have ensured that my code changes pass unit tests.
• I have described my pull request and the reasons for code changes along with context if necessary.

[titanism]

❤️ it - would love undici here (writing because we're actually implementing custom retry logic as a simple wrapper for undici)

[titanism]

@jimmywarting feel free to merge this PR if it's ready