Add JSON APIs for submission details and use them in SolutionChecker.py

[veluca93]

No description provided.

[codecov]

Codecov Report

❌ Patch coverage is 87.42058% with 99 lines in your changes missing coverage. Please review.
✅ Project coverage is 56.65%. Comparing base (6ca9c9f) to head (28936c8).
✅ All tests successful. No failed tests found.

Files with missing lines	Patch %	Lines
cmscontrib/SolutionChecker.py	74.16%	77 Missing ⚠️
cms/server/contest/handlers/api.py	80.64%	12 Missing ⚠️
cms/grading/scoretypes/abc.py	91.07%	5 Missing ⚠️
cms/grading/scoretypes/Sum.py	85.00%	3 Missing ⚠️
...suite/unit_tests/cmscontrib/SolutionCheckerTest.py	99.43%	1 Missing ⚠️
cmstestsuite/unit_tests/server/contest/api_test.py	99.07%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1712      +/-   ##
==========================================
+ Coverage   55.47%   56.65%   +1.17%     
==========================================
  Files         342      344       +2     
  Lines       27551    28234     +683     
==========================================
+ Hits        15285    15997     +712     
+ Misses      12266    12237      -29     

Flag	Coverage Δ
functionaltests	0.00% <0.00%> (ø)
unittests	56.65% <87.42%> (+1.17%)	⬆️

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