feat: Run Applitools on public Storybook

[geido]

SUMMARY

This PR introduces a Github workflow to test the Storybook Netlify instance nightly (at midnight).

The flow works as follows:

• Netlify builds a Storybook on every push on master. The built Storybook instance is publicly available here: Superset Storybook. No action is required from our side as Netlify watches the repo and does the build automatically
• The Github workflow included in this PR will test the Storybook instance nightly at midnight using Applitools

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 #19852 (e6da33f) into master (90130e4) will decrease coverage by 0.03%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master   #19852      +/-   ##
==========================================
- Coverage   66.56%   66.52%   -0.04%     
==========================================
  Files        1714     1715       +1     
  Lines       65043    65055      +12     
  Branches     6723     6723              
==========================================
- Hits        43293    43278      -15     
- Misses      20037    20066      +29     
+ Partials     1713     1711       -2     

Flag	Coverage Δ
javascript	51.26% <ø> (-0.05%)	⬇️

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

Impacted Files	Coverage Δ
...rd/components/nativeFilters/FilterBar/keyValue.tsx	33.33% <0.00%> (-18.52%)	⬇️
...board/components/nativeFilters/FilterBar/index.tsx	60.58% <0.00%> (-7.30%)	⬇️
superset/views/datasource/views.py	90.21% <0.00%> (-6.45%)	⬇️
superset/utils/cache.py	74.52% <0.00%> (-0.48%)	⬇️
superset/sql_lab.py	81.32% <0.00%> (-0.32%)	⬇️
superset/views/core.py	77.02% <0.00%> (-0.04%)	⬇️
superset/models/core.py	89.33% <0.00%> (ø)
superset/db_engine_specs/sqlite.py	97.29% <0.00%> (ø)
superset/charts/commands/importers/v1/__init__.py	100.00% <0.00%> (ø)
superset/models/sql_types/base.py	52.63% <0.00%> (ø)
... and 3 more

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[eschutho]

This is so cool!