Add Events to ABCIMessageLog

[alexanderbez]

closes: #4990

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• Targeted PR against correct branch (see CONTRIBUTING.md)

• Linked to github-issue with discussion and accepted design OR link to spec that describes this work.

• Wrote tests

• Updated relevant documentation (docs/)

• Added a relevant changelog entry to the Unreleased section in CHANGELOG.md

• Re-reviewed Files changed in the github PR explorer

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For Admin Use:

• Added appropriate labels to PR (ex. wip, ready-for-review, docs)
• Reviewers Assigned
• Squashed all commits, uses message "Merge pull request #XYZ: [title]" (coding standards)

[codecov]

Codecov Report

Merging #5032 into master will increase coverage by 0.73%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master    #5032      +/-   ##
==========================================
+ Coverage   54.81%   55.55%   +0.73%     
==========================================
  Files         291      287       -4     
  Lines       17844    17541     -303     
==========================================
- Hits         9782     9745      -37     
+ Misses       7357     7096     -261     
+ Partials      705      700       -5