Refactor drop webpack@4

[cap-Bernardito]

This PR contains a:

• bugfix
• new feature
• code refactor
• test update
• typo fix
• metadata update

Motivation / Use-Case

drop webpack@4

Breaking Changes

Yes

Additional Info

No

[codecov]

Codecov Report

Merging #675 (61c44e8) into master (359c00f) will decrease coverage by 0.38%.
The diff coverage is 97.84%.

@@            Coverage Diff             @@
##           master     #675      +/-   ##
==========================================
- Coverage   88.75%   88.36%   -0.39%     
==========================================
  Files          11       11              
  Lines         676      576     -100     
  Branches      184      148      -36     
==========================================
- Hits          600      509      -91     
+ Misses         73       66       -7     
+ Partials        3        1       -2     

Impacted Files	Coverage Δ
src/index.js	96.12% <97.75%> (+4.77%)	⬆️
src/loader.js	90.90% <100.00%> (-1.72%)	⬇️
src/CssModule.js	50.66% <0.00%> (-5.34%)	⬇️
src/utils.js	84.61% <0.00%> (-3.85%)	⬇️

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