Add feature checking logic for engine API

Add feature checking logic for engine API

- Issue:
Most of the engine API did not return 'not supported error' when the
device does not support the TTS feature.

- Solution:
This patch adds feature checking logic to the beginning of each API
implementation. Through this change, each API will properly check the
required feature and return error. And this behavior is matched to the
description of each API.

Change-Id: I744cb3bbeb6670f3fdfedc1ecd3f9d710f822be2
Signed-off-by: Suyeon Hwang <stom.hwang@samsung.com>