fix(explore): make to show the null value as N/A in view result

[prosdev0107]

SUMMARY

NULL values not showing up in View Results in Explore

BEFORE/AFTER SCREENSHOTS OR ANIMATED GIF

BEFORE:

AFTER:

TESTING INSTRUCTIONS

How to reproduce bugs

1. Go to Explore.
2. Create or Open the Table Chart
3. When looking at a table with Null values, the View Results section didn't show the null values.

ADDITIONAL INFORMATION

• 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 #19603 (12f1a74) into master (f91f83d) will increase coverage by 0.02%.
The diff coverage is 50.00%.

@@            Coverage Diff             @@
##           master   #19603      +/-   ##
==========================================
+ Coverage   66.65%   66.68%   +0.02%     
==========================================
  Files        1680     1681       +1     
  Lines       64292    64310      +18     
  Branches     6564     6566       +2     
==========================================
+ Hits        42854    42884      +30     
+ Misses      19736    19732       -4     
+ Partials     1702     1694       -8     

Flag	Coverage Δ
javascript	51.52% <50.00%> (+0.06%)	⬆️

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

Impacted Files	Coverage Δ
.../src/explore/components/DataTableControl/index.tsx	70.66% <50.00%> (-0.96%)	⬇️
...frontend/src/views/CRUD/alert/AlertReportModal.tsx	52.08% <0.00%> (-0.30%)	⬇️
...ntend/packages/superset-ui-core/src/color/utils.ts	100.00% <0.00%> (ø)
...c/views/CRUD/data/database/DatabaseModal/index.tsx	32.79% <0.00%> (ø)
...ins/legacy-plugin-chart-partition/src/Partition.js	0.00% <0.00%> (ø)
...ins/legacy-plugin-chart-sankey/src/ReactSankey.jsx	0.00% <0.00%> (ø)
...s/legacy-plugin-chart-horizon/src/HorizonChart.jsx	0.00% <0.00%> (ø)
...acy-plugin-chart-paired-t-test/src/PairedTTest.jsx	0.00% <0.00%> (ø)
...rt-parallel-coordinates/src/ParallelCoordinates.js	0.00% <0.00%> (ø)
...allel-coordinates/src/ReactParallelCoordinates.jsx	0.00% <0.00%> (ø)
... and 7 more

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