refactor(trie): extract save_hashed_storages closure to method2

[Himess]

Closes #566 (2/5)

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 38.26%. Comparing base (01da650) to head (61542a3).
⚠️ Report is 5 commits behind head on unstable.

Additional details and impacted files

Files with missing lines	Coverage Δ
crates/optimism/trie/src/backfill.rs	91.57% <100.00%> (+1.64%)	⬆️

... and 12 files with indirect coverage changes

Flag	Coverage Δ
e2e	35.65% <100.00%> (-0.13%)	⬇️
unit	26.90% <100.00%> (+0.01%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Components	Coverage Δ
reth binary	53.14% <ø> (ø)
op historical proof	90.07% <100.00%> (+0.10%)	⬆️

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[dhyaniarun1993]

Thank you @Himess for contribution.
Could you resolve the conflicts and add other methods to this PR?

[dhyaniarun1993]

superseded by #578