build(webpack): use [contenthash] instead of [chunkhash]

[nytai]

SUMMARY

Webpack's chunkhash is not reliable and produces different hashes for builds of the same assets. Using contenthash is far more reliable for caching dependencies based on content.

More info available in this issue webpack/webpack#7179

BEFORE/AFTER SCREENSHOTS OR ANIMATED GIF

N/A

TESTING INSTRUCTIONS

• npm run build produces a working prod build

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 #14942 (5be1e18) into master (8cc97e4) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master   #14942   +/-   ##
=======================================
  Coverage   77.57%   77.57%           
=======================================
  Files         964      964           
  Lines       49385    49385           
  Branches     6238     6238           
=======================================
  Hits        38310    38310           
  Misses      10874    10874           
  Partials      201      201           

Flag	Coverage Δ
javascript	72.36% <ø> (ø)

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