feat: add support for 8MiB sector size

[th7nder]

Description

Partially fixes #664. As it only adds 8MiB support as an example.

Important points for reviewers

It successfully creates 8MiB sector, but still cannot store arbitrary files, there is another issue with padding. I'm investigating in another task. (fixed in #709) and allows to store arbitrary files. Maat test has been adjusted for that, along with other dependencies that were not creating CAR files properly.

Checklist

• Are there important points that reviewers should know?
  • If yes, which ones?
• Make sure that you described what this change does.
• If there are follow-ups, have you created issues for them?
  • If yes, which ones? / List them here
    • Cannot store arbitrary file because of padding #709
• Have you tested this solution?
• Were there any alternative implementations considered?
• Did you document new (or modified) APIs?

[jmg-duarte]

Blocking until #709 is addressed

[aidan46]

👍

[jmg-duarte]

lgtm