[WIP] Switch JSON parsing library

[PietrH]

Questions

• Can we drop the {jsonlite} direct dependency entirely?
• jsonlite remains an indirect dependency via httr2 where it is Suggests anyway

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 88.01%. Comparing base (05379c9) to head (0e48f49).

Additional details and impacted files

@@                      Coverage Diff                       @@
##           388-get-acoustic-citations     #503      +/-   ##
==============================================================
+ Coverage                       87.95%   88.01%   +0.05%     
==============================================================
  Files                              27       27              
  Lines                             822      826       +4     
==============================================================
+ Hits                              723      727       +4     
  Misses                             99       99              

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