[CrOS MultiDevice] Create shared multidevice_types.mojom.

This CL moves RemoteDevice, BeaconSeed, SoftwareFeature, and
SoftwareFeatureState to a shared multidevice_types.mojom file, cleanly
separating them from the DeviceSync service. Previously, these Mojo
definitions were part of that service even though they are shared among
several services, so including them as part of DeviceSync created an
unnecessary dependency on that service which shouldn't exist.

Change-Id: Ie20cd22f63bd35441c1a5879d71bb5fd3c473bf4
Bug: 912743
Reviewed-on: https://chromium-review.googlesource.com/c/1363905
Reviewed-by: Ryan Hansberry <hansberry@chromium.org>
Reviewed-by: Demetrios Papadopoulos <dpapad@chromium.org>
Reviewed-by: Steven Bennetts <stevenjb@chromium.org>
Reviewed-by: Daniel Cheng <dcheng@chromium.org>
Reviewed-by: Ken Rockot <rockot@google.com>
Commit-Queue: Kyle Horimoto <khorimoto@chromium.org>
Cr-Commit-Position: refs/heads/master@{#614828}
28 files changed