[feature] Debug mode for parser CLI

[digizeph]

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When debugging MRT files, it is often useful to display more detailed information in a different format (like bgpmon or libparsebgp).

Desired features:

• [ ] display layered debug information for records (no-splitting to elements)
• [ ] filter by matching attribute types (looking for records with specific attributes)
• [ ] dump message bytes into hex text format