move-only: Move *Disk functions to blockstorage

Summary:
Can be reviewed with the git options
--color-moved=dimmed-zebra --color-moved-ws=ignore-all-space

This is a backport of core#21575 [4/6]
https://github.com/bitcoin/bitcoin/pull/21575/commits/fa0c7d9ad24d3c9515d3f9c136af4071cbd79055

Depends on D11349 and D11355

Notes:

• we don't have the ReadRawBlockFromDisk functions, which are related to segwit
• some functions were in blockdb.{h|cpp} rather than validation.{h|cpp} in Bitcoin ABC. blockdb.{h|cpp} will most likely be unnecessary and deleted as a result of this series of backports.

Test Plan: ninja all check-all

Reviewers: #bitcoin_abc, Fabien

Reviewed By: #bitcoin_abc, Fabien

Differential Revision: https://reviews.bitcoinabc.org/D11350