Add prettify helper to make types more readable.

[wjhsf]

For ShopperBaskets<{shortCode: string; organizationId: string}>['getBasket'], the type is displayed as:

(method) ShopperBaskets<{ shortCode: string; organizationId: string; }>.getBasket(options?: ({
    parameters?: (Omit<{
        organizationId: string;
        basketId: string;
        siteId: string;
        locale?: string | undefined;
    }, "organizationId" | "shortCode"> & Partial<{
        organizationId: string;
        basketId: string;
        siteId: string;
        locale?: string | undefined;
    }>) | undefined;
    headers?: {
        ...;
    } | undefined;
} & Required<...>) | undefined): Promise<...> (+1 overload)

With this change, it's significantly easier to read:

(method) ShopperBaskets<{ shortCode: string; organizationId: string; }>.getBasket(options?: {
    parameters: {
        siteId: string;
        locale?: string | undefined;
        basketId: string;
        organizationId?: string | undefined;
    };
    headers?: {
        [key: string]: string;
    } | undefined;
} | undefined): Promise<...> (+1 overload)