RLP Block importer does not validate block headers against engine API rules

[macfarla]

eg this test https://hive.ethpandaops.io/pectra/suite.html?suiteid=1742771993-dd8981844476302696757189d4fe81e8.json&suitename=eest%2Fconsume-rlp#

there are 3 failing for the same reason - eg
tests/cancun/eip4844_blobs/test_excess_blob_gas_fork_transition.py::test_invalid_pre_fork_block_with_blob_fields[fork_ShanghaiToCancunAtTime15k-blockchain_test-excess_blob_gas_present_False-blob_gas_used_present_True]

expects that if the block header has blobGasUsed present, it will fail import. This validation occurs within EngineNewPayloadV2 but because these hive tests use RLPBlockImporter, they don't go through the EngineAPI. Would be nice to refactor so we can have the same validation happen here.

Description:
Test id: tests/cancun/eip4844_blobs/test_excess_blob_gas_fork_transition.py::test_invalid_pre_fork_block_with_blob_fields[fork_ShanghaiToCancunAtTime15k-blockchain_test-excess_blob_gas_present_False-blob_gas_used_present_True]

Test source: https://github.com/ethereum/execution-spec-tests/tree/v4.1.0/tests/cancun/eip4844_blobs/test_excess_blob_gas_fork_transition.py#L207

Test function documentation:

Test block rejection when `excessBlobGas` and/or `blobGasUsed` fields are present on a pre-fork
block.

Blocks sent by NewPayloadV2 (Shanghai) that contain `excessBlobGas` and `blobGasUsed` fields
must be rejected with the appropriate `EngineAPIError.InvalidParams` error error.

[jflo]

Fork specific validation rules should be pushed down for maximum reuse based on the protocol schedule, and failures need to be finely grained enough that the EngineAPI using it can convey correct errors back up to the client.

[jflo]

Needs design work.

It is also possible that this test, as implemented is overly dependent on a reference implementation instead of a spec.