windows: add virtual key codes and console input consts

This adds console input related key codes and consts

Change-Id: I8ebd76995a2c9ddd150cf04890a9e5053841fcab
GitHub-Last-Rev: 8e534f4589e57f1d681e72877917578a0ed67622
GitHub-Pull-Request: golang/sys#226
Reviewed-on: https://go-review.googlesource.com/c/sys/+/621495
Reviewed-by: Junyang Shao <shaojunyang@google.com>
Auto-Submit: Michael Pratt <mpratt@google.com>
Reviewed-by: Michael Pratt <mpratt@google.com>
Reviewed-by: Alex Brainman <alex.brainman@gmail.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>