Change enum Version to enum class Version

It is possible to accidentally call the Windows GetVersion() function
when base::win::GetVersion() is intended. The code would compile due to
implicit conversions from enum to int. This allowed buggy code to be
checked in.

Using enum class makes this error impossible. This change switches
enum Version to enum class Version, which includes changing every usage
of the Version enum.

For services\service_manager
TBR=wfh@chromium.org
For the rest
TBR=jochen@chromium.org

Bug: 946677
Change-Id: I4b446370499e5e6a24446d18b541e2b4948405e8
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1541594
Reviewed-by: Bruce Dawson <brucedawson@chromium.org>
Reviewed-by: Daniel Cheng <dcheng@chromium.org>
Commit-Queue: Bruce Dawson <brucedawson@chromium.org>
Cr-Commit-Position: refs/heads/master@{#652728}
160 files changed