refactor(fs): remove rayon dependency

[nathanwhitbot]

Summary

• Removes the direct rayon dependency from deno_fs while preserving parallel recursive-copy work with a standard-library worker queue.
• Drops the rayon, rayon-core, and crossbeam-deque runtime graph path from the deno normal dependency tree where applicable.
• Preserves the existing recursive copy behavior, metadata lookup, recursive call flow, and per-entry error context.

Validation

• cargo fmt --check
• cargo test -p deno_fs
• cargo tree -p deno --edges normal --target x86_64-unknown-linux-gnu --prefix none
• CARGO_TARGET_DIR=<scratch>/target-before cargo build --bin deno --target x86_64-unknown-linux-gnu
• CARGO_TARGET_DIR=<scratch>/target-after cargo build --bin deno --target x86_64-unknown-linux-gnu
• Compared dependency graph/count and debug binary size before and after on the same target, verifying the debug binary did not increase.

[bartlomieju]

Ditto, this appears to not use parallelizm anymore