This change adds a command line parameter for instantiating a VVU proxy
device.
BUG=b:194136484
TEST=Test with sibling VM with Vhost master connecting to a device VM.
Change-Id: I5ff56e6f1ebca5a7078eca3d951ddbfd411d14fc
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/crosvm/+/3290381
Reviewed-by: Chirantan Ekbote
Reviewed-by: Keiichi Watanabe <keiichiw@chromium.org>
Tested-by: kokoro <noreply+kokoro@google.com>
Commit-Queue: Abhishek Bhardwaj <abhishekbh@chromium.org>
