fix(linter/unicorn): do not report on optionals in prefer-array-flat-map

[baevm]

fixes commented out tests for optionals in #19428

[Copilot]

Pull request overview

This PR updates the Unicorn prefer-array-flat-map rule to avoid reporting (and therefore auto-fixing) map().flat() patterns when optional chaining is involved, re-enabling previously skipped upstream test cases.

Changes:

• Skip diagnostics when the outer .flat() call is an optional call (.flat?.() / ?.flat()).
• Skip diagnostics when the .flat member access is optionally chained (?.flat).
• Skip diagnostics when the inner .map call is an optional call (map?.(…)), and re-enable the associated pass tests.

[codspeed-hq]

Merging this PR will not alter performance

✅ 4 untouched benchmarks
⏩ 47 skipped benchmarks¹

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_{Comparing baevm:prefer-array-flat-map-fix-optionals (7e31434) with main (2484e3e)²}

Footnotes

1. 47 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩

2. No successful run was found on main (7ac69fa) during the generation of this report, so 2484e3e was used instead as the comparison base. There might be some changes unrelated to this pull request in this report. ↩