Function indy_sys::payments::indy_add_request_fees

#[no_mangle]
pub unsafe extern "C" fn indy_add_request_fees(
    command_handle: Handle, 
    wallet_handle: Handle, 
    submitter_did: CString, 
    req_json: CString, 
    inputs_json: CString, 
    outputs_json: CString, 
    extra: CString, 
    cb: Option<ResponseStringStringCB>
) -> Error