L1->L2 message hashes are 256 bit hashes

[AnkushinDaniil]

L1 Message Hash Parsing Fix

Problem

L1 message hashes (Keccak256 output) were parsed as felts, causing errors for some hash values that exceed the felt range.

Solution

• Introduced a new Hash256 type to represent 256-bit hash values.
• Updated L1 transaction receipt to use Hash256 for message hashes.

This change ensures correct parsing and handling of Keccak256 hash outputs in L1 messages.

P2P protocol specification change: starknet-io/starknet-p2p-specs#46