chore: changed publishing approach

[gionkunz]

I read through https://github.com/webpack/webpack/issues/4674 and changed the publishing approach accordingly.

[codecov-commenter]

Codecov Report

Merging #1323 (32d74ef) into develop (3f4d63f) will not change coverage. The diff coverage is n/a.

@@           Coverage Diff            @@
##           develop    #1323   +/-   ##
========================================
  Coverage    73.76%   73.76%           
========================================
  Files           42       42           
  Lines         1231     1231           
  Branches       322      322           
========================================
  Hits           908      908           
  Misses         239      239           
  Partials        84       84           

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[dangreen]

@gionkunz Hi. Webpack should receive ESM treeshakable bundle , but now it will use iife bundle from browser field. Also it's not UMD bundle but named like that. UMD bundle builds for main field (you can see it in Rollup config). I sugges you to revert this PR.