fix: SQL Lab UI Error: Objects are not valid as a React child

[diegomedina248]

SUMMARY

When the query result doesn't have any information nor is it stored in the api, the resultsKey returns null (as expected) and the query table in the SQL Lab crashes.

This PR renders a placeholder in that case to prevent it, since if the query failed, there's nothing to display in the "results" column.

BEFORE/AFTER SCREENSHOTS OR ANIMATED GIF

Before:

164038206-370664ac-96b6-4329-a76e-8c2fcb0e2b06.mov

After:

Screen.Recording.2022-04-19.at.17.25.37.mov

TESTING INSTRUCTIONS

Follow the instructions from #19746

ADDITIONAL INFORMATION

Fixes #19746

• Has associated issue:
• Required feature flags:
• Changes UI
• Includes DB Migration (follow approval process in SIP-59)
  • Migration is atomic, supports rollback & is backwards-compatible
  • Confirm DB migration upgrade and downgrade tested
  • Runtime estimates and downtime expectations provided
• Introduces new feature or API
• Removes existing feature or API

[codecov]

Codecov Report

Merging #19783 (8d73dc6) into master (6f4480a) will increase coverage by 0.00%.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##           master   #19783   +/-   ##
=======================================
  Coverage   66.51%   66.51%           
=======================================
  Files        1690     1690           
  Lines       64616    64615    -1     
  Branches     6656     6655    -1     
=======================================
+ Hits        42978    42979    +1     
+ Misses      19937    19936    -1     
+ Partials     1701     1700    -1     

Flag	Coverage Δ
javascript	51.19% <100.00%> (+<0.01%)	⬆️

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

Impacted Files	Coverage Δ
...rontend/src/SqlLab/components/QueryTable/index.tsx	70.17% <100.00%> (+0.53%)	⬆️
superset-frontend/src/utils/urlUtils.ts	46.93% <0.00%> (ø)
...dashboard/components/SliceHeaderControls/index.tsx	66.66% <0.00%> (ø)
.../components/ExploreAdditionalActionsMenu/index.jsx	57.14% <0.00%> (ø)
...dashboard/components/menu/ShareMenuItems/index.tsx	90.00% <0.00%> (+8.18%)	⬆️

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[villebro]

LGTM!