refactor: riseapi mode response format

[IgnatovFedor]

If Chainer returns ["a0", "a1", "a2"], riseapi response format is changed from [["a0"], ["a1"], ["a2"]] to ["a0", "a1", "a2"]. If Chainer returns (["a0", "a1", "a2"], ["b0", "b1", "b2"]), riseapi response format is changed from [["a0", "b0"], ["a1", "b1"], ["a2", "b2"]] to [["a0", "a1", "a2"], ["b0", "b1", "b2"]].