feat(reliable-integration): emit VERTEX_METADATA_CHANGED events in reverse topological order

[glevco]

Motivation

To help Reliable Integration use cases, it would be better to emit VERTEX_METADATA_CHANGED events in topological order from right to left. This can be achieved by sorting by decreasing transaction timestamp.

Acceptance Criteria

• Change events emitted from consensus to sorted by reverse timestamp instead of hash

Checklist

• If you are requesting a merge into master, confirm this code is production-ready and can be included in future releases as soon as it gets merged

[codecov]

Codecov Report

All modified lines are covered by tests ✅

Comparison is base (aadaf75) 84.64% compared to head (68d1edc) 84.74%.
Report is 9 commits behind head on master.

❗ Current head 68d1edc differs from pull request most recent head 57126e4. Consider uploading reports for the commit 57126e4 to get more accurate results

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #776      +/-   ##
==========================================
+ Coverage   84.64%   84.74%   +0.10%     
==========================================
  Files         260      259       -1     
  Lines       21951    21939      -12     
  Branches     2965     2964       -1     
==========================================
+ Hits        18581    18593      +12     
+ Misses       2722     2703      -19     
+ Partials      648      643       -5     

Files	Coverage Δ
hathor/consensus/consensus.py	97.89% <100.00%> (ø)

... and 6 files with indirect coverage changes

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