Refactor OpenVR test class names to be runtime agnostic

Rename two test classes that currently have "OpenVR" in its name. These
classes do not have OpenVR specific implementations and can be
generalized to support other runtimes.

- OpenVRTestHook -> VRTestHook. The file is also moved from
/device/vr/openvr/test to /device/vr/test.
- MockOpenVRDeviceHookBase -> MockVRDeviceHookBase

Change-Id: I7b8ecad096e7c787d39a59fd7308fc25fdc904db
Reviewed-on: https://chromium-review.googlesource.com/c/1479813
Commit-Queue: Patrick To <patrto@microsoft.com>
Reviewed-by: Bill Orr <billorr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#636572}
18 files changed