dynamic lambda: current round awareness for AttachReceivedAt, AttachValidatedAt

[cce]

Summary

This lets AttachReceivedAt and AttachValidatedAt know what the player's current round is, so that they can handle setting timestamps for messages for R+1 better (these are called pipelined votes or proposals). Instead of using the clock for round R they set a timestamp of 1ns for these pipelined messages, since they have arrived before cert quorum was locally observed on R.

Test Plan

Updated existing tests to provide currentRound.

[codecov]

Codecov Report

❌ Patch coverage is 84.61538% with 4 lines in your changes missing coverage. Please review.
✅ Project coverage is 55.29%. Comparing base (529278a) to head (326561c).

Files with missing lines	Patch %	Lines
agreement/events.go	81.81%	4 Missing ⚠️

Additional details and impacted files

@@                    Coverage Diff                     @@
##           feature/dynamic-lambda    #5715      +/-   ##
==========================================================
+ Coverage                   55.26%   55.29%   +0.03%     
==========================================================
  Files                         474      474              
  Lines                       66244    66260      +16     
==========================================================
+ Hits                        36608    36639      +31     
+ Misses                      27172    27156      -16     
- Partials                     2464     2465       +1     

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[cce]

@yossigi adapted and added to the end of #5654, closing