Updates to IDEX L1 code for consistency

[bourque]

There are a few updates we can make to the IDEX L1 code to be more consistent with other instruments' pipelines:

• Generate an updated packet definition file with recent version of space_packet_parser
• Separate out the L0 decommutation code and the L1 processing code within idex_packet_parser.py, and update unit tests accordingly
• Switch CDF attribute definitions to use yaml files instead of dataclasses
• ~Add call to write_cdf() within pipeline so that CDFs get created within the pipeline, instead of within cli.py~

[subagonsouth]

You may want to hold off on that final bullet. I think that @greglucas had some compelling reasons as to why the pipelines should not be calling write_cdf().