Describe the bug

ASCReader in python-can 4.1.0 doesn't support ASC CANFD format since V8.1, since <symbolic_name> name is missing in code.
According to the document from Vector <can_log_trigger_asc_format.pdf>, there should be <SYMBOLIC_NAME> between <ID> and <BRS>.

To Reproduce

Use python-can to read CANFD message in asc log since format V8.1.

Expected behavior

Reading process stopped with CANFD message.

Additional context

I made a quick fix in a forked branch.
I think an overall fix about ASC format IO is needed in this issue.

OS and version:
Python version:
python-can version:
python-can interface/s (if applicable):