Migrate from Babel to SWC

[julianweng]

• Migrate to SWC for faster compilation performance
• Use built-in Next.js SWC Styled Components support
• Replace Istanbul Babel plugin with SWC plugin (for continuity, not sure if this works or is needed since we don't really have tests or a frontend check step anymore)

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 71.95%. Comparing base (1f7cdfe) to head (77f5993).
Report is 1 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master     #751   +/-   ##
=======================================
  Coverage   71.95%   71.95%           
=======================================
  Files          32       32           
  Lines        6952     6952           
=======================================
  Hits         5002     5002           
  Misses       1950     1950           

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[aviupadhyayula]

LGTM, thanks for taking the lead on this Julian. Don't have much context here but trust that you've got this handled.