refactor: sql_json view endpoint: separate save query concern

[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 sixth PR in the sequence of future PRs (previous PR) try to solve it by refactoring the code.
The PR focus of separate "save new query" concern into ad hod method so the code will be cleaner
there are no logic changes so it implies on the current tests.

[codecov]

Codecov Report

Merging #16646 (c569a3f) into master (6465ee7) will decrease coverage by 0.14%.
The diff coverage is 66.66%.

@@            Coverage Diff             @@
##           master   #16646      +/-   ##
==========================================
- Coverage   76.70%   76.56%   -0.15%     
==========================================
  Files        1004     1004              
  Lines       53983    53983              
  Branches     7335     7335              
==========================================
- Hits        41408    41332      -76     
- Misses      12336    12412      +76     
  Partials      239      239              

Flag	Coverage Δ
hive	?
mysql	81.55% <66.66%> (-0.04%)	⬇️
postgres	81.62% <66.66%> (+<0.01%)	⬆️
python	81.70% <66.66%> (-0.28%)	⬇️
sqlite	81.27% <66.66%> (+<0.01%)	⬆️

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

Impacted Files	Coverage Δ
superset/views/core.py	75.70% <66.66%> (+0.07%)	⬆️
superset/db_engines/hive.py	0.00% <0.00%> (-82.15%)	⬇️
superset/db_engine_specs/hive.py	69.80% <0.00%> (-16.87%)	⬇️
superset/views/database/mixins.py	81.03% <0.00%> (-1.73%)	⬇️
superset/db_engine_specs/presto.py	83.47% <0.00%> (-1.05%)	⬇️
superset/db_engine_specs/base.py	88.00% <0.00%> (-0.39%)	⬇️
superset/connectors/sqla/models.py	88.04% <0.00%> (-0.24%)	⬇️
superset/utils/core.py	89.76% <0.00%> (-0.13%)	⬇️

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[amitmiran137]

Simple method extraction
LGTM!