Add to set playing mode to decide where the synthesized pcm data will be played

Add to set playing mode to decide where the synthesized pcm data will be played

Needs: The application wants to play the synthesized pcm data on client side.

Solution: Provides the Api to set playing mode to decide where it will be played.

This commit is related to following commit.
https://review.tizen.org/gerrit/#/c/platform/core/uifw/tts/+/284933/

Change-Id: If9e73f05409feab8e9ff371aee1570b38d6e2407