Usability and formatting improvements for codegen-py

[lreiher]

• add full generation command to all auto-generated files as a comment

  # --- Auto-generated by https://github.com/ika-rwth-aachen/etsi_its_messages ---
  # python3 \
  #   utils/codegen/codegen-py/asn1ToRosMsg.py \
  #   asn1/raw/cam_en302637_2/CAM-PDU-Descriptions.asn \
  #   asn1/raw/cam_en302637_2/cdd/ITS-Container.asn \
  #   -t \
  #   cam \
  #   -o \
  #   etsi_its_msgs/etsi_its_cam_msgs/msg
  # ------------------------------------------------------------------------------

• add raw ASN.1 definitions to conversion headers as a comment (already existing in .msg files)

  /** ASN.1 Definition -----------------------------------------------------------
  CAM ::= SEQUENCE {
      header ItsPduHeader,
      cam CoopAwareness
  }
  ----------------------------------------------------------------------------- */

• add progress bars to code generation scripts

  Parsing ASN.1 files ...
  Generating conversion headers: 100%|█████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████| 153/153 [00:00<00:00, 899.80it/s, PhoneNumber]
  Removing files not required for top-level message type ...
  Generated 94 conversion headers for CAM
  

• color warnings in code generation scripts in yellow
• optimize linebreaks in conversion header templates to remove one empty line after each memset

[lreiher]

@jpbusch: Please review before I'm pushing all generated code changes.

[jpbusch]

Ready for file generation