Update EIP-7799: Validate systemLogsRoot in engine_newPayloadVx instead of forkchoiceUpdated

[MozirDmitriy]

• Problem: The spec incorrectly required validating systemLogsRoot during engine_forkchoiceUpdated. Engine API payload field validations (e.g., receiptsRoot, withdrawals_root) occur at payload acceptance in engine_newPayloadVx, not during fork choice updates.
• Change: Moved the validation requirement to engine_newPayloadVx and specified rejection of invalid payloads (e.g., INVALID).
• Impact: Aligns with established Engine API semantics, prevents transient acceptance of invalid payloads, and matches how clients validate new payloads.

[eth-bot]

File EIPS/eip-7799.md

Requires 1 more reviewers from @etan-status, @g11tech

[etan-status]

engine_newPayload does not necessarily trigger processing (e.g., ACCEPTED result, if a block gets imported from a different branch). Such processing is delayed until engine_forkchoiceUpdated.

engine_newPayload only does minimal validation to guarantee that the block hash matches the content (otherwise, one could disconnect them and build on top of an invalid chain or even create loops).