feat: update redb to v2 (#2120)

## Description

`redb` 2.0.0 was released:
https://github.com/cberner/redb/releases/tag/v2.0.0

most relevant for us: 
> 2.0.0 uses a new file format that optimizes len() to be constant time.
This means that it is not backwards compatible with 1.x. To upgrade,
consider using a pattern like that shown in the
[upgrade_v1_to_v2](https://github.com/cberner/redb/blob/222a37f4600588261b0983eebcd074bb69d6e5a0/tests/backward_compatibility.rs#L282-L299)
test.

and some nice API changes that will simplify the iroh-sync codebase (no
more ouroboros for self-refential structs needed!)

> * Remove lifetimes from read-only tables
> * Remove lifetime from WriteTransaction and ReadTransaction

and some further API changes, see the notes.

---

* [x] Update iroh-bytes to redb v2
* Did some crude search&replaces to remove now unneeded lifetime bounds.
Compiles now, let's see what test says.
* [x] Migration for iroh-bytes db
* Code adapted from here
https://github.com/n0-computer/migrate-bao-store-redb/blob/main/src/main.rs
* [x] Update  iroh-sync to redb v2
* This will be a bit more involved as iroh-bytes because we hit more API
changes, but also great because we can remove `ouroborous` because
iterators can now own a range
* [x] Migration for iroh-sync db

The migrations likely need a dependency to redb v1 to read the old
database, so at least for one release cycle we'll have to depend on both
redb v2 and v1.

## Notes & open questions

This currently includes an extra-safeguard by preserving the old
databases for sync and blobs as `docs.redb.backup-redb-v1` and
`blobs.db-backup-redb-v1` - do we want this or delete the backups after
successfull migration?


## Change checklist

- [x] Self-review.
- [ ] Documentation updates if relevant.
- [ ] Tests if relevant.

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Co-authored-by: Friedel Ziegelmayer <[email protected]>