refactor(assert): vendor code from fmt/colors.ts

[iuioiua]

Towards #4717

[codecov]

Codecov Report

Attention: Patch coverage is 89.47368% with 6 lines in your changes are missing coverage. Please review.

Project coverage is 91.44%. Comparing base (4398642) to head (a26dbe3).

Files	Patch %	Lines
internal/styles.ts	88.67%	6 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4716      +/-   ##
==========================================
- Coverage   91.44%   91.44%   -0.01%     
==========================================
  Files         480      481       +1     
  Lines       37318    37371      +53     
  Branches     5316     5318       +2     
==========================================
+ Hits        34126    34173      +47     
- Misses       3136     3142       +6     
  Partials       56       56              

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[iuioiua]

Frankly, I'd prefer we minimize our use of colors as much as possible.

[kt3k]

Maybe this only makes sense when we reached a consensus on #4676

[iuioiua]

How does that issue affect this PR?

[kt3k]

If we don't move fmt/colors (and stabilize it as is), then we don't need to do this

[iuioiua]

Then stabilizing std/fmt would block the stabilization of std/internal and std/assert, and stabilizing std/fmt is not yet on the radar. This PR allows us to make these moves asynchronously. I think we should proceed with this PR, even if we change things later.

[kt3k]

Ok. Makes sense

[kt3k]

LGTM