[Raiden/FaultTolerance] Support chunk header version compatibility validation and version-dependent parsing

[copybara-service]

[Raiden/FaultTolerance] Support chunk header version compatibility validation and version-dependent parsing

Why:

• Support rolling upgrades with 1-version backward compatibility before modifying ChunkHeader wire format.
• v1 and v2 wire formats remain identical in this CL, establishing the versioning infrastructure first so subsequent changes can safely modify wire layouts.

What:

• Set current version to 2 (kChunkHeaderCurrentVersion = 2) and support incoming versions 1 and 2.
• Reject unsupported versions (diff >= 2) with FailedPreconditionError.
• Dispatch incoming deserialization in DeserializeChunkHeader based on version:

  switch (ver) {
    case 1: return DeserializeHeaderV1(h1, header);
    case 2: return DeserializeHeaderV2(h2, header);
    default: return absl::FailedPreconditionError(...);
  }

• Enforce serializing only current version 2 with DCHECK_EQ(header.version, kChunkHeaderCurrentVersion).

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