refactor: sql_json view endpoint: move all logic from view to Command class

[ofekisr]

SUMMARY
The sql_json view code in superset core view without any "clean code" standard and it does not adopt any software development principle.

This is the thirteenth PR in the sequence of future PRs (previous PR) try to solve it by refactoring the code.

The PR focus on separating all the logic of sql-json-execution to command class so the logic and view layers will be separated

actually, there are no logic changes so it implies on the current tests.

[codecov]

Codecov Report

Merging #16682 (64b3071) into master (1cc7263) will decrease coverage by 0.13%.
The diff coverage is 83.66%.

❗ Current head 64b3071 differs from pull request most recent head 4fc2219. Consider uploading reports for the commit 4fc2219 to get more accurate results

@@            Coverage Diff             @@
##           master   #16682      +/-   ##
==========================================
- Coverage   76.93%   76.79%   -0.14%     
==========================================
  Files        1005     1007       +2     
  Lines       54049    54086      +37     
  Branches     7339     7339              
==========================================
- Hits        41581    41536      -45     
- Misses      12228    12310      +82     
  Partials      240      240              

Flag	Coverage Δ
hive	?
mysql	?
postgres	81.67% <83.33%> (-0.04%)	⬇️
presto	81.54% <83.66%> (+0.02%)	⬆️
python	81.95% <83.66%> (-0.28%)	⬇️
sqlite	81.31% <83.33%> (+0.02%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
superset/sqllab/command.py	82.35% <82.35%> (ø)
superset/sqllab/command_status.py	100.00% <100.00%> (ø)
superset/views/core.py	75.80% <100.00%> (-0.83%)	⬇️
superset/db_engines/hive.py	0.00% <0.00%> (-82.15%)	⬇️
superset/db_engine_specs/hive.py	69.80% <0.00%> (-16.87%)	⬇️
superset/db_engine_specs/mysql.py	94.04% <0.00%> (-3.58%)	⬇️
superset/models/core.py	88.63% <0.00%> (-0.78%)	⬇️
superset/connectors/sqla/models.py	89.46% <0.00%> (-0.24%)	⬇️
superset/utils/core.py	89.76% <0.00%> (-0.13%)	⬇️
... and 2 more

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[amitmiran137]

nice decoupling the view layer and logic into a command that encapsulates query execution into a result object