refactor: icon to icons for headeractionsdropdown

[pkdotson]

SUMMARY

This pr refactors the icon to icons component for the headeractionsdropdown more-horiz icon.

BEFORE/AFTER SCREENSHOTS OR ANIMATED GIF

before

after

TESTING INSTRUCTIONS

Go to a dashboard to test the new icon

ADDITIONAL INFORMATION

• Has associated issue:
• 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 #15560 (ed6adf3) into master (314d49c) will increase coverage by 0.08%.
The diff coverage is 35.71%.

❗ Current head ed6adf3 differs from pull request most recent head 2ba72fe. Consider uploading reports for the commit 2ba72fe to get more accurate results

@@            Coverage Diff             @@
##           master   #15560      +/-   ##
==========================================
+ Coverage   76.86%   76.95%   +0.08%     
==========================================
  Files         976      976              
  Lines       51320    51291      -29     
  Branches     6912     6907       -5     
==========================================
+ Hits        39446    39469      +23     
+ Misses      11655    11603      -52     
  Partials      219      219              

Flag	Coverage Δ
javascript	71.41% <100.00%> (+0.02%)	⬆️

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

Impacted Files	Coverage Δ
superset/config.py	91.15% <28.00%> (-5.89%)	⬇️
.../components/Header/HeaderActionsDropdown/index.jsx	67.50% <100.00%> (+0.41%)	⬆️
superset/app.py	83.33% <100.00%> (+19.84%)	⬆️
superset-frontend/src/components/Select/Select.tsx	0.00% <0.00%> (ø)
superset/models/core.py	90.02% <0.00%> (+0.26%)	⬆️
superset/connectors/sqla/models.py	89.90% <0.00%> (+1.40%)	⬆️
superset/db_engine_specs/presto.py	90.31% <0.00%> (+5.89%)	⬆️

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