Generate class diagram documentation for new Beckn v2

Similar to `https://raw.githubusercontent.com/beckn/protocol-specifications-v2/refs/heads/p2p-trading/docs/schema/core/v2/attributes.svg`
generated using https://github.com/beckn/protocol-specifications-v2/blob/p2p-trading/scripts/generate_schema_diagrams.sh

in https://github.com/beckn/protocol-specifications-v2/tree/p2p-trading/docs/schema


