Return json object on /scripts endpoint as documented in OpenAPI

[illia-malachyn]

Work on #2601

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 41.32%. Comparing base (ca70376) to head (5b0019c).

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #6412      +/-   ##
==========================================
- Coverage   41.46%   41.32%   -0.15%     
==========================================
  Files        2016     1898     -118     
  Lines      143726   133790    -9936     
==========================================
- Hits        59595    55287    -4308     
+ Misses      77954    72881    -5073     
+ Partials     6177     5622     -555     

Flag	Coverage Δ
unittests	41.32% <ø> (-0.15%)	⬇️

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[illia-malachyn]

TODO:
test for error need to be fixed;
update openapi schema with base64 format for scriptBody.args;
figure out why one test path fails;