sync2: implement malfeasance sync

[ivan4th]

sync2: implement malfeasance sync

Motivation

We need to use syncv2 for malfeasance proofs

Description

This adds syncv2 based reconciliation for malfeasance proofs.
Active sync of malfeasance proofs is feature-gated.

Test Plan

Test on mainnet nodes

TODO

• Explain motivation or link existing issue(s)
• Test changes and document test plan
• Update documentation as needed
• Update changelog as needed

[codecov]

Codecov Report

Attention: Patch coverage is 84.05797% with 33 lines in your changes missing coverage. Please review.

Project coverage is 79.9%. Comparing base (8595fcc) to head (3ef6421).
Report is 1 commits behind head on develop.

✅ All tests successful. No failed tests found.

Files with missing lines	Patch %	Lines
sync2/commitstate.go	83.3%	10 Missing and 3 partials ⚠️
syncer/syncer.go	80.0%	8 Missing and 4 partials ⚠️
sync2/p2p.go	50.0%	4 Missing ⚠️
sync2/malfeasance.go	90.9%	2 Missing and 1 partial ⚠️
sync2/atxs.go	90.0%	1 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff            @@
##           develop   #6650    +/-   ##
========================================
  Coverage     79.9%   79.9%            
========================================
  Files          366     368     +2     
  Lines        49551   49666   +115     
========================================
+ Hits         39610   39703    +93     
- Misses        7699    7722    +23     
+ Partials      2242    2241     -1     

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