Move the app_service code to //chrome/services

The app_service code was originally created under //chrome/browser,
specifically //chrome/browser/apps/foundation. This was because of an
early concern that the app_service implementation would need to be
tightly coupled to browser concepts, especially a Profile. More recent
prototyping suggests that this won't be the case.

This is just a "git mv" plus some semi-mechanical clean-up, e.g. keeping
"#include" lines sorted.

Change-Id: I0e511f5cab636afb7ac5e5235139873d75230377
Reviewed-on: https://chromium-review.googlesource.com/c/1312435
Reviewed-by: Dominic Battré <battre@chromium.org>
Reviewed-by: Avi Drissman <avi@chromium.org>
Reviewed-by: Ken Rockot <rockot@google.com>
Reviewed-by: Dominick Ng <dominickn@chromium.org>
Commit-Queue: Nigel Tao <nigeltao@chromium.org>
Cr-Commit-Position: refs/heads/master@{#605876}