MB: Flip Windows bots to GN by default
MB: Flip Windows bots to GN by default

Change the previous GN configs to build GYP instead
(since we'll keep GYP around for a while) but exclude tests
and examples for that config, since we'll only support the production
code for GYP.

Add new configs for upcoming rename of those bots to GYP instead
of GN.

BUG=webrtc:5949
NOTRY=True

Review-Url: https://codereview.webrtc.org/2277253002
Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#13946}

ShiftMediaProject/libilbc,TimothyGu/libilbc,TimothyGu/libilbc,ShiftMediaProject/libilbc,ShiftMediaProject/libilbc,ShiftMediaProject/libilbc,TimothyGu/libilbc,TimothyGu/libilbc,ShiftMediaProject/libilbc,TimothyGu/libilbc