Function parse_order_accepted 

pub fn parse_order_accepted(
    msg: &DeribitOrderMsg,
    instrument: &InstrumentAny,
    account_id: AccountId,
    trader_id: TraderId,
    strategy_id: StrategyId,
    ts_init: UnixNanos,
) -> OrderAccepted

Parses a Deribit order message into an OrderAccepted event.

This should be called when an order transitions to “open” state for the first time or when a buy/sell response is received successfully.