Changes to User Positions

removed the required property positions/items/initial_margin from the response with the 200 status

added the new optional query request parameter api_version

added the optional property balance/isolated_equity to the response with the 200 status

added the optional property positions/items/isolated_available to the response with the 200 status

added the optional property positions/items/isolated_collateral to the response with the 200 status

added the optional property positions/items/margin_mode to the response with the 200 status

added the required property balance/builder_rewards to the response with the 200 status

added the required property positions/items/margin to the response with the 200 status