In the deposit, the `swh_anchor_id` is now of the form:
```
swh:1:dir:<hash>;?origin=<origin>;visit=<snp-hash>;...
```
Where it was of the form:
```
swh:1:dir:<hash>;?origin=<origin>
```
This adapts the extraction to take into account the new format and provides the
`end` of the `data.slice` call.
Related to T1398
Related to T2409