feat: smt verification

[hansieodendaal]

Description

Fix an issue where the SMT should not be verified for each block height while horizon sync is in progress, but only at the end.

Motivation and Context

The SMT can only be verified after all outputs have been downloaded, due to the way we optimize fetching
outputs from the sync peer. As an example:

1. Initial sync:
   • We request outputs from height 0 to 100 (the tranche)
   • The sync peer only returns outputs per block that would still be unspent at height 100 and all
     inputs per block. All outputs that were created and spent within the tranche are never returned.
   • For example, an output is created in block 50 and spent in block 70. It would be included in the SMT
     for headers from height 50 to 69, but due to the optimization, the sync peer would never know about it.
2. Consecutive sync:
   • We request outputs from height 101 to 200 (the tranche)
   • The sync peer only returns outputs per block that would still be unspent at height 200, as well as all
     inputs per block, but in this case, only those inputs that are not an output of the current tranche of
     outputs. Similarly, all outputs created and spent within the tranche are never returned.
   • For example, an output is created in block 110 and spent in block 180. It would be included in the SMT
     for headers from height 110 to 179, but due to the optimization, the sync peer would never know about it.
3. In both cases it would be impossible to verify the SMT per block, as we would not be able to update the
   SMT with the outputs that were created and spent within the tranche.

How Has This Been Tested?

System-level horizon sync test using a previous archival node that was converted to a pruned node.

What process can a PR reviewer use to test or verify this change?

Code review

Breaking Changes

• None
• Requires data directory on base node to be deleted
• Requires hard fork
• Other - Please specify

[github-actions]

Test Results (CI)

1 268 tests   1 268 ✅  11m 32s ⏱️
   39 suites      0 💤
    1 files        0 ❌

Results for commit e044133.

♻️ This comment has been updated with latest results.

[github-actions]

Test Results (Integration tests)

 2 files  + 2  11 suites  +11   14m 2s ⏱️ + 14m 2s
29 tests +29  28 ✅ +28  0 💤 ±0  1 ❌ +1 
31 runs  +31  29 ✅ +29  0 💤 ±0  2 ❌ +2 

For more details on these failures, see this check.

Results for commit e044133. ± Comparison against base commit b6b80f6.

♻️ This comment has been updated with latest results.