chore: Moves spec files to the src folder - iteration 10

[michael-s-molina]

SUMMARY

• Moves spec files to the src folder - iteration 10
• Standardizes the extension of the test files

This work is part of SIP-61

TESTING INSTRUCTIONS

1 - Execute all tests
2 - All tests should pass

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 #17902 (1e86d2e) into master (8ebec60) will decrease coverage by 0.00%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master   #17902      +/-   ##
==========================================
- Coverage   67.10%   67.09%   -0.01%     
==========================================
  Files        1609     1610       +1     
  Lines       64897    64913      +16     
  Branches     6866     6870       +4     
==========================================
+ Hits        43547    43556       +9     
- Misses      19484    19490       +6     
- Partials     1866     1867       +1     

Flag	Coverage Δ
javascript	53.77% <ø> (+<0.01%)	⬆️

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

Impacted Files	Coverage Δ
superset-frontend/src/explore/fixtures.tsx	70.00% <ø> (ø)
superset-frontend/src/setup/setupColors.ts	73.33% <0.00%> (-8.49%)	⬇️
...l/AdhocFilterEditPopoverSimpleTabContent/index.tsx	66.18% <0.00%> (-0.97%)	⬇️
superset-frontend/src/middleware/asyncEvent.ts	69.46% <0.00%> (ø)
superset-frontend/src/common/components/index.tsx	100.00% <0.00%> (ø)
...ntend/packages/superset-ui-core/src/color/index.ts	100.00% <0.00%> (ø)
...ashboard/components/gridComponents/ChartHolder.jsx	58.82% <0.00%> (ø)
...s/legacy-plugin-chart-country-map/src/countries.ts	100.00% <0.00%> (ø)
...mponents/nativeFilters/FiltersConfigModal/state.ts	73.33% <0.00%> (ø)
...end/src/common/hooks/useComponentDidMount/index.ts
... and 37 more

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