Prep for retiring Jackson-flavored ELM

[JPercival]

• Remove elm-jackson dependencies whereever possible, and swap to elm-jaxb
• Change tests that expect Jackson-flavored ELM to expect JAXB-flavored ELM
• Fixed slf4j version mismatch. Upstream project (HAPI) introduced 2.0.13

[github-actions]

Formatting check succeeded!

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 64.49%. Comparing base (0fb9698) to head (51cd26a).
Report is 1 commits behind head on master.

Additional details and impacted files

@@             Coverage Diff              @@
##             master    #1485      +/-   ##
============================================
+ Coverage     64.45%   64.49%   +0.03%     
  Complexity     1939     1939              
============================================
  Files           494      494              
  Lines         28154    28154              
  Branches       5593     5593              
============================================
+ Hits          18146    18157      +11     
+ Misses         7745     7722      -23     
- Partials       2263     2275      +12     

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[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud