Add event serialization testing

[DanSava]

Issue
Resolves #9517

Approach
Add serialization roundtrip for all events generated by EverestRunModel

• PR title captures the intent of the changes, and is fitting for release notes.
• Added appropriate release note label
• Commit history is consistent and clean, in line with the contribution guidelines.
• Make sure unit tests pass locally after every commit (git rebase -i main --exec 'pytest tests/ert/unit_tests -n logical -m "not integration_test"')

When applicable

• When there are user facing changes: Updated documentation
• New behavior or changes to existing untested code: Ensured that unit tests are added (See Ground Rules).
• Large PR: Prepare changes in small commits for more convenient review
• Bug fix: Add regression test for the bug
• Bug fix: Create Backport PR to latest release

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 96.77419% with 2 lines in your changes missing coverage. Please review.

Project coverage is 91.74%. Comparing base (790933d) to head (9cfb9d8).
Report is 22 commits behind head on main.

Files with missing lines	Patch %	Lines
src/ert/ensemble_evaluator/snapshot.py	94.11%	1 Missing ⚠️
src/ert/run_models/event.py	97.67%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #9573      +/-   ##
==========================================
+ Coverage   91.71%   91.74%   +0.02%     
==========================================
  Files         429      426       -3     
  Lines       26672    26589      -83     
==========================================
- Hits        24463    24393      -70     
+ Misses       2209     2196      -13     

Flag	Coverage Δ
cli-tests	39.80% <41.93%> (+0.09%)	⬆️
everest-models-test	34.16% <40.32%> (+0.02%)	⬆️
gui-tests	74.23% <41.93%> (+2.42%)	⬆️
integration-test	37.98% <40.32%> (-0.29%)	⬇️
performance-tests	51.55% <41.93%> (-0.11%)	⬇️
test	39.52% <40.32%> (-0.05%)	⬇️
unit-tests	74.27% <96.77%> (+0.28%)	⬆️

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[codspeed-hq]

CodSpeed Performance Report

Merging #9573 will degrade performances by 10.59%

_{Comparing DanSava:test-event-serialization (9cfb9d8) with main (7b2bedf)}

Summary

❌ 1 regressions
✅ 23 untouched benchmarks

⚠️ Please fix the performance issues or acknowledge them on CodSpeed.

Benchmarks breakdown

	Benchmark	main	DanSava:test-event-serialization	Change
❌	test_direct_dark_performance_with_storage[gen_x: 20, sum_x: 20 reals: 10-summary-get_record_observations]	1.3 ms	1.5 ms	-10.59%