fix(fs): root fs promises iterator state

[andrewtdiz]

Closes #800.

Summary

• root fs/promises FileHandle iterator state and Dir dirent entries during GC
• preserve built-in named import metadata so aliased fs/promises open and opendir infer FileHandle/Dir results
• route for await over fs.Dir and dir.entries() through the async iterator loop instead of sync materialization

Tests

• PATH=/root/.npm/_npx/bac97da9607b7ef2/node_modules/.bin:$PATH PERRY_NO_AUTO_OPTIMIZE=1 timeout 900 ./run_parity_tests.sh --suite node-suite --module fs-promises --filter filehandle-readlines
• PATH=/root/.npm/_npx/bac97da9607b7ef2/node_modules/.bin:$PATH PERRY_NO_AUTO_OPTIMIZE=1 timeout 900 ./run_parity_tests.sh --suite node-suite --module fs-promises --filter opendir-iteration-disposal
• PATH=/root/.npm/_npx/bac97da9607b7ef2/node_modules/.bin:$PATH PERRY_NO_AUTO_OPTIMIZE=1 timeout 900 ./run_parity_tests.sh --suite node-suite --module fs-promises (81 pass / 0 fail)
• cargo fmt --all -- --check
• git diff --check
• ./scripts/check_file_size.sh
• cargo check -q -p perry-hir -p perry-runtime