test: add property-based tests for ak.array_equal

[TaiSakuma]

Following #3887, this PR adds another property-based test.

• The PR adds property-based test for ak.array_equal().
• This test is more fundamental than those for ak.to_buffers() and ak.from_buffers(), added in test: introduce property-based testing with to_buffers/from_buffers roundtrip #3887
• I should've added this test first.
• The test fails currently.
• It will be easier to write other tests when this test passes.
• The code is generated by Claude Code.
• I'm writing this PR description.
• Claude Code will open a PR with the GitHub CLI.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 71.16%. Comparing base (1584bf8) to head (dd4e396).
⚠️ Report is 2 commits behind head on main.

Additional details and impacted files

see 60 files with indirect coverage changes

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[github-actions]

The documentation preview is ready to be viewed at http://preview.awkward-array.org.s3-website.us-east-1.amazonaws.com/PR3891

[ikrommyd]

This will need to wait for the fixes that I’m doing.