Start mini-ARCVM in ArcVmClientAdapter::StartMiniArc()

This change modifies ArcVmClientAdapter to start ARCVM before
login (to implement mini-ARC). Among the changes are:
 - Starts mini-ARCVM with a generic user kArcVmDefaultOwner
 - Sets correct owner id during UpgradeArc()
 - Stops VM if UpgradeArc() fails
 - On StopArcInstance(), checks if mini-ARC or full ARC is running
 - Update unittests

BUG=b:144542975
TEST=ArcVmClientAdapterTest unittests
TEST=tast run <DUT> arc.Boot.vm crostini.Basic.buster_amd64_stable
TEST=build and flash. On login screen, check chrome log and syslog
to make sure ARCVM has started successfully. Check guest logcat and
make sure init is blocked on arcvm-boot-notification-client. After
login, check that instance is upgraded successfully and Play Store
is able to start.

Change-Id: I190a9ede041b53f0dbcb1773ea82b2e0ac51ae54
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2354623Reviewed-by: Ryo Hashimoto <hashimoto@chromium.org>
Reviewed-by: Yusuke Sato <yusukes@chromium.org>
Commit-Queue: Willie Koomson <wvk@google.com>
Cr-Commit-Position: refs/heads/master@{#840674}

chromeos/dbus/fake_concierge_client.h

@@ -252,6 +252,10 @@ class COMPONENT_EXPORT(CHROMEOS_DBUS) FakeConciergeClient
           resize_disk_image_response) {
     resize_disk_image_response_ = resize_disk_image_response;
   }
+  void set_set_vm_id_response(
+      base::Optional<vm_tools::concierge::SetVmIdResponse> set_vm_id_response) {
+    set_vm_id_response_ = set_vm_id_response;
+  }
 
   void set_send_create_disk_image_response_delay(base::TimeDelta delay) {
     send_create_disk_image_response_delay_ = delay;