feat/ adding expiration to open orders endpoint

[poly-rodr]

This PR adds two new fields to the OpenOrder structure:

• expiration: string, unix timestamp when the order expired, 0 if it does not expire
• type: string, order type (GTC, FOK, GTD).

Complete OpenOrder data type:

export interface OpenOrder {
    id: string;
    status: string;
    owner: string;
    market: string;
    asset_id: string;
    side: string;
    original_size: string;
    size_matched: string;
    price: string;
    associate_trades: Trade[];
    outcome: string;
    outcome_index: number;
    created_at: number;
    type: string;
}