[OnionSoup] Move payment_{app,request}.mojom into blink/public/mojom/

As part of Onion Soup effort, blink/public/mojom/payments/ should be the
right place for payment_{app,request}.mojom, this CL moves them there
from blink/public/platform/modules/payments/.

This movement facilitates moving
//content/common/service_worker/service_worker.mojom into
blink/public/mojom/service_worker/ in future.

BUG=789854

Change-Id: Idaa2abacfefe706d05acbe8f23a7daea00f4ab66
Reviewed-on: https://chromium-review.googlesource.com/1192687
Commit-Queue: Han Leon <leon.han@intel.com>
Reviewed-by: Lei Zhang <thestig@chromium.org>
Reviewed-by: Marijn Kruisselbrink <mek@chromium.org>
Reviewed-by: Kinuko Yasuda <kinuko@chromium.org>
Reviewed-by: Rouslan Solomakhin <rouslan@chromium.org>
Reviewed-by: Kentaro Hara <haraken@chromium.org>
Cr-Commit-Position: refs/heads/master@{#587416}
53 files changed