C++ porting of the initial python script for conversational speech generation.

This CL removes the Python script and adds its C++ porting.
The former was in its early stage and it has permanently been removed.

BUG=webrtc:7218
NOTRY=True

Review-Url: https://codereview.webrtc.org/2740063004
Cr-Original-Commit-Position: refs/heads/master@{#17254}
Cr-Mirrored-From: https://chromium.googlesource.com/external/webrtc
Cr-Mirrored-Commit: 0cf3aa6d0d170365a2dedb57960fbface736f851
9 files changed