add a round trip test to the fuzzer

[phlptp]

This is the next phase of the fuzzer. It runs a round trip and makes sure that the config files generated by the app will load into the same results, to test full round trip on the config files.

Issues fixed

• fix a bug in the string escape code caught by initial round trip tests
• resolve inconsistencies in handling of {} for empty vector indication between config and cli parsing

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 100.00%. Comparing base (e4ee3af) to head (83694dc).
Report is 35 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##              main     #1060    +/-   ##
==========================================
  Coverage   100.00%   100.00%            
==========================================
  Files           17        17            
  Lines         4546      4599    +53     
  Branches         0       987   +987     
==========================================
+ Hits          4546      4599    +53     

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