t8n: Include empty requests[Hash] in JSON output - hardcoded

[pdobacz]

Hardcoded version of #1064

Fixes #1062

If the sha256 refactor from #1064 is not useful, we can just roll with this

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 94.23%. Comparing base (39daf04) to head (cd8210c).
Report is 3 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #1065   +/-   ##
=======================================
  Coverage   94.22%   94.23%           
=======================================
  Files         158      158           
  Lines       17054    17059    +5     
=======================================
+ Hits        16069    16075    +6     
+ Misses        985      984    -1     

Flag	Coverage Δ
eof_execution_spec_tests	17.81% <0.00%> (-0.01%)	⬇️
ethereum_tests	26.53% <0.00%> (-0.01%)	⬇️
ethereum_tests_silkpre	19.12% <0.00%> (-0.01%)	⬇️
execution_spec_tests	20.24% <0.00%> (-0.01%)	⬇️
unittests	89.27% <100.00%> (+<0.01%)	⬆️

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Files with missing lines	Coverage Δ
test/t8n/t8n.cpp	87.03% <100.00%> (+1.04%)	⬆️

[pdobacz]

close in favor of the original #1064