fix(saved-query): handle case where sql_tables in undefined

[nytai]

SUMMARY

Handles case where sql_tables is undefined in the api response. see linked issue for details.

BEFORE/AFTER SCREENSHOTS OR ANIMATED GIF

N/A

TEST PLAN

manually tested following steps listed in the linked issue

ADDITIONAL INFORMATION

• Has associated issue: Fixes Saved Queries Page Doesn't Load After User Tries to Save a Blank Query #11647
• Changes UI
• Requires DB Migration.
• Confirm DB Migration upgrade and downgrade tested.
• Introduces new feature or API
• Removes existing feature or API

[codecov-io]

Codecov Report

Merging #11649 (65004fb) into master (091432e) will decrease coverage by 4.32%.
The diff coverage is 0.00%.

@@            Coverage Diff             @@
##           master   #11649      +/-   ##
==========================================
- Coverage   66.59%   62.26%   -4.33%     
==========================================
  Files         876      873       -3     
  Lines       42146    42303     +157     
  Branches     3943     3971      +28     
==========================================
- Hits        28066    26342    -1724     
- Misses      13977    15781    +1804     
- Partials      103      180      +77     

Flag	Coverage Δ
cypress	?
javascript	62.84% <0.00%> (+0.27%)	⬆️
python	61.92% <ø> (-0.23%)	⬇️

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

Impacted Files	Coverage Δ
.../src/views/CRUD/data/savedquery/SavedQueryList.tsx	61.36% <0.00%> (-0.47%)	⬇️
superset-frontend/src/SqlLab/App.jsx	0.00% <0.00%> (-100.00%)	⬇️
superset-frontend/src/explore/App.jsx	0.00% <0.00%> (-100.00%)	⬇️
superset-frontend/src/dashboard/App.jsx	0.00% <0.00%> (-100.00%)	⬇️
superset-frontend/src/explore/index.jsx	0.00% <0.00%> (-100.00%)	⬇️
superset-frontend/src/dashboard/index.jsx	0.00% <0.00%> (-100.00%)	⬇️
superset-frontend/src/setup/setupColors.js	0.00% <0.00%> (-100.00%)	⬇️
superset-frontend/src/chart/ChartContainer.jsx	0.00% <0.00%> (-100.00%)	⬇️
superset-frontend/src/setup/setupFormatters.js	0.00% <0.00%> (-100.00%)	⬇️
superset-frontend/src/explore/reducers/index.js	0.00% <0.00%> (-100.00%)	⬇️
... and 199 more

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