Drop legacy require support

[mstoykov]

What?

Completely drop the legacy require support

Why?

Checklist

• [ ] I have performed a self-review of my code.
• [ ] I have added tests for my changes.
• [ ] I have run linter locally (make lint) and all checks pass.
• [ ] I have run tests locally (make tests) and all tests pass.
• [ ] I have commented on my code, particularly in hard-to-understand areas.

Related PR(s)/Issue(s)

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 80.95238% with 8 lines in your changes are missing coverage. Please review.

Project coverage is 70.87%. Comparing base (93649df) to head (2961d5a).

:exclamation: Current head 2961d5a differs from pull request most recent head af21b6f

Please upload reports for the commit af21b6f to get more accurate results.

Files	Patch %	Lines
js/bundle.go	77.77%	2 Missing and 2 partials :warning:
js/modules/resolution.go	82.60%	2 Missing and 2 partials :warning:

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #3694      +/-   ##
==========================================
- Coverage   70.88%   70.87%   -0.01%     
==========================================
  Files         291      288       -3     
  Lines       21226    21183      -43     
==========================================
- Hits        15045    15013      -32     
+ Misses       5216     5206      -10     
+ Partials      965      964       -1     

Flag	Coverage Δ
ubuntu	70.87% <80.95%> (+0.03%)	:arrow_up:
windows	?

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[mstoykov]

This is now part of #3456