Backlog for Express 6.x

This issue includes a reference to all the PRs/issues or pending tasks for Express and dependencies needed to finally ship new versions of Express@6.x

### Rules (WIP):
- If something is completed, just marked
- If there is a PR/Issue/Discussion please add it (try to use one item)
- If there is someone taking ownership on it, please add it. Ownership means to be the focal point for it not necessarily the person who makes the final change.
- If there is no leader, feel free to claim it.
- If you can no longer lead something, just let others claim it back
- As this issue can have many comments, feel free to address them and then mark the original comment as "outdated" ([details](https://docs.github.com/en/communities/moderating-comments-and-conversations/managing-disruptive-comments#hiding-a-comment)) so it is easier to follow.

If you think that any reference is missing, please edit this comment (@expressjs/express-tc) or reply with a comment if you don't have the permissions.

### Agreed to be part of Express 6.x

_none yet_

### Whislist / Ideas:

**New (require discussion)**

- [ ] https://github.com/expressjs/discussions/issues/407
- [ ] https://github.com/expressjs/express/pull/3730
- [ ] https://github.com/expressjs/express/pull/3214
- [ ] https://github.com/expressjs/express/pull/3218
- [ ] https://github.com/expressjs/express/pull/3213
- [ ] https://github.com/expressjs/express/pull/2648
- [ ] https://github.com/expressjs/body-parser/pull/524
- [ ] https://github.com/jshttp/on-finished/pull/31 (@UlisesGascon)

**Discarted**

_none_

**Won't happen**

_none_