jest-diff: Rename some new options and change their default values

[pedrottimark]

Summary

1. Split and rename trailingSpaceFormatter option as prerequisite to improve snapshot colors:

   • changeLineTrailingSpaceColor because aColor and bColor might have background color
   • commonLineTrailingSpaceColor because dim does not modify like other colors

2. Rename firstOrLastEmptyLineReplacement as emptyFirstOrLastLinePlaceholder

3. Change default values so dependents can turn them on instead of need to turn them off (not breaking, because the new options have not yet been published)

4. Edit README.md table and examples of new options

5. Provide explicit values for these options in jest-matcher-utils and jest-snapshot

6. Export DiffOptionsColor type so jest-snapshot can declare getSnapshotColor and getReceivedColor with conditional expression of chalk.level to return improved colors

Test plan

In jest-diff package:

• diff.test.ts add 1 test and update 2 tests for trailingSpaceFormatter
• joinAlignedDiffs.test.ts add emptyFirstOrLastLinePlaceholder which affects 3 tests

[SimenB]

I agree this is easier to grok 👍

[github-actions]

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