jest-diff: Add trailingSpaceFormatter option and replace cyan with commonColor

[pedrottimark]

Summary

1. Make default export and diffStringsUnified display trailing spaces consistently:

   • default export used chalk.inverse in changed lines, but it is ambiguous with formatting for changed substrings
   • default export used chalk.bgYellow in common lines, which becomes the default value of the option, unless y’all recommend something else
   • diffStringsUnified used '·' middle dot, but it is ambiguous with content

2. Replace cyan color with commonColor for lines that differ only by indentation when both values are objects (am studying how to do it for snapshots tests when received is object and snapshot is string)

Residue

• diffStringsUnified replaces trimmable empty line at beginning or end of diff with '↵' but default export does not
• chore to omit double quote marks and have consistent length for color tags in diffs.test.ts.snap

Test plan

package	file	snapshots
expect	matchers.test.ts.snap	updated 2
jest-diff	diffs.test.ts.snap	updated 1 , added 2, deleted 5
jest-matcher-utils	printDiffOrStringify.test.ts	updated 1
jest-snapshot	printDiffOrStringified.test.ts	updated 1

See also pictures in the following comment

[codecov-io]

Codecov Report

Merging #8927 into master will decrease coverage by 0.04%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master    #8927      +/-   ##
==========================================
- Coverage   64.28%   64.24%   -0.05%     
==========================================
  Files         276      276              
  Lines       11716    11695      -21     
  Branches     2868     2863       -5     
==========================================
- Hits         7532     7513      -19     
+ Misses       3552     3550       -2     
  Partials      632      632

Impacted Files	Coverage Δ
packages/jest-diff/src/normalizeDiffOptions.ts	100% <ø> (ø)	⬆️
packages/jest-diff/src/printDiffs.ts	97.4% <100%> (-0.04%)	⬇️
packages/jest-diff/src/diffLines.ts	96.77% <100%> (-0.35%)	⬇️
packages/jest-environment-jsdom/src/index.ts	38.63% <0%> (-0.5%)	⬇️
packages/jest-transform/src/ScriptTransformer.ts	68.77% <0%> (-0.15%)	⬇️
packages/jest-environment-node/src/index.ts	48.48% <0%> (-0.09%)	⬇️
packages/jest-fake-timers/src/FakeTimersLolex.ts	69.76% <0%> (ø)	⬆️

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[pedrottimark]

Baseline at left and improved at right

default export from potentially confusing inverse to bgYellow

lines which differ only by indentation become dim

diffStringsUnified from dot to bgYellow

and inverse color for space means it is a change

Baseline at left and optional at right

now it is possible for options to specify no colors

const noColor = string => string;

const options = {
  aColor: noColor,
  bColor: noColor,
  changeColor: noColor,
  commonColor: noColor,
  patchColor: noColor,
  trailingSpaceFormatter: noColor,
};

[SimenB]

Nice, I like it!

[github-actions]

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