refactor(Radio): address component QA feedback

[booc0mtaco]

• stop using radio icons which can now be removed
• replace with styling using in-DOM elements (future proof for transitions)
• better application of color tokens
• add tests
• update snapshots

Test Plan:

• Wrote automated tests
• CI tests / new tests are not applicable
• Manually tested my changes, but I want to keep the details secret
• Created and used an alpha publish
• Manually tested my changes, and here are the details:

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 97.31%. Comparing base (f6e280f) to head (abbb511).

Additional details and impacted files

@@                  Coverage Diff                   @@
##           v15-components-2.0    #1986      +/-   ##
======================================================
+ Coverage               96.77%   97.31%   +0.54%     
======================================================
  Files                     142      142              
  Lines                    3629     3615      -14     
  Branches                 1000      998       -2     
======================================================
+ Hits                     3512     3518       +6     
+ Misses                    114       94      -20     
  Partials                    3        3              

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