chore(allocator, data_structures, lexer, traverse): enable undocumented_unsafe_blocks clippy lint

[overlookmotel]

Enable undocumented_unsafe_blocks clippy lint rule, and fix warnings it raises.

[overlookmotel]

• chore(allocator, data_structures, lexer, traverse): enable undocumented_unsafe_blocks clippy lint #9363 👈 (View in Graphite)
• main

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[codspeed-hq]

CodSpeed Performance Report

Merging #9363 will not alter performance

_{Comparing 02-25-chore_allocator_data_structures_lexer_traverse_enable_undocumented_unsafe_blocks_clippy_lint (4f2fc39) with main (e3b6eeb)}

Summary

✅ 33 untouched benchmarks

[Boshen]

Merge activity

• Feb 25, 9:04 PM EST: The merge label '0-merge' was detected. This PR will be added to the Graphite merge queue once it meets the requirements.
• Feb 25, 9:05 PM EST: A user added this pull request to the Graphite merge queue.
• Feb 25, 9:10 PM EST: A user merged this pull request with the Graphite merge queue.