Remaining Engine API Cancun Tests

[marioevz]

Extracted list of remaining tasks for Cancun Engine API from #759

### Tasks
- [ ] Implement tests for https://github.com/ethereum/execution-apis/pull/426
- [ ] Field checking of new engine api methods, pre and post fork
- [ ] Sync Tests
- [ ] Parallelism Tests
- [ ] Auto-generate README.md from the information in the test case list

[jochem-brouwer]

This seems currently untested:

• forkchoiceUpdatedV2 throws INVALID_PARAMS if parentBlockBeaconRoot is provided
• forkchoiceUpdatedV3 throws UNSUPPORTED_FORK if it is called at < Cancun time
• getPayloadV3 throws UNSUPPORTED_FORK if a pre-Cancun payload is requested