fix(ef-tests): seal engine typo and deserialization

[rkrasiuk]

Description

• fix typo: self_engine -> seal_engine
• fix SealEngine deserialization: should be PascalCase instead of camelCase. see json schema

NOTE: contrary to the schema we omit SealEngine::Ethash since it has been deprecated and no longer used

[codecov]

Codecov Report

Merging #4997 (8df4faf) into main (505c6bc) will decrease coverage by 0.02%.
Report is 5 commits behind head on main.
The diff coverage is n/a.

see 43 files with indirect coverage changes

Flag	Coverage Δ
integration-tests	15.85% <ø> (+0.44%)	⬆️
unit-tests	62.41% <ø> (-0.12%)	⬇️

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Components	Coverage Δ
reth binary	30.61% <ø> (-0.01%)	⬇️
blockchain tree	80.64% <ø> (ø)
pipeline	88.37% <ø> (-0.09%)	⬇️
storage (db)	74.40% <ø> (ø)
trie	94.51% <ø> (+0.03%)	⬆️
txpool	48.27% <ø> (-0.04%)	⬇️
networking	76.43% <ø> (+0.33%)	⬆️
rpc	57.96% <ø> (+0.01%)	⬆️
consensus	63.01% <ø> (ø)
revm	27.89% <ø> (+0.10%)	⬆️
payload builder	7.96% <ø> (ø)
primitives	86.29% <ø> (-0.06%)	⬇️