Add script to generate GN/MSVS projects.
Add script to generate GN/MSVS projects.

BUG=angleproject:1569

Change-Id: I0e47720d17cd1a29603e471482cac31d4c281ee5
Reviewed-on: https://chromium-review.googlesource.com/735059
Reviewed-by: Geoff Lang <b6fc25fe0362055230985c05cbfa8adb741ccc0f@chromium.org>
Commit-Queue: Jamie Madill <7e492b4f1c8458024932de3ba475cbf015424c30@chromium.org>

ppy/angle,ppy/angle,ppy/angle,ppy/angle