op-reth: Fix reth-primitives signature tests

[BrianBland]

Updates signature tests in reth-primitives to be compatible with the special-case optimism serialization for zero signatures (R: 0, S: 0, V: 0).

Adds optimism-only test cases for this zero signature behavior

Fixes the following tests:

reth-primitives transaction::signature::tests::test_encode_and_decode_with_eip155_chain_id
reth-primitives transaction::signature::tests::test_payload_len_with_eip155_chain_id
reth-primitives transaction::signature::tests::test_v