Values for mainnet and testnet will be specified in a follow-up PR that can be
scrutinized accordingly. This structure is required for use in snapshot activation
logic.
This is a backport of [[https://github.com/bitcoin/bitcoin/pull/19806 | core#19806]] [4/8]
https://github.com/bitcoin/bitcoin/pull/19806/commits/7a6c46b37edb8bfa0085d202aa7e9427d5e4fceb
Notes:
The hash values for the regtest network must be adjusted to work with Bitcoin ABC. The correctness of these two hashes will be tested when `chainstatemanager_activate_snapshot` is implemented in a next commit. The new test introduced in this diff only tests that these hardcoded hashes will not be accidentaly or maliciously modified.
The new circular dependency was added by core in a later commit. We already need it here.