added CANFD support

[superuserx]

Checklist:

• [ ] If you are new to Scapy: I have checked CONTRIBUTING.md (esp. section submitting-pull-requests)
• [ ] I squashed commits belonging together
• [ ] I added unit tests or explained why they are not relevant
• [ ] I executed the regression tests (using cd test && ./run_tests or tox)
• [ ] If the PR is still not finished, please create a Draft Pull Request

fixes #xxx