devices: vvu-proxy: Introduce enum representing connection status
devices: vvu-proxy: Introduce enum representing connection status

BUG=b:232273004, b:b:216407443
TEST=cargo build

Change-Id: Ic3fecab7d3c04cdd09f5c77b849c1fac7ee43f7b
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/crosvm/+/3640875
Tested-by: kokoro <2ac7b1f3fa578934c95181d4272be0d3bca00121@google.com>
Reviewed-by: Abhishek Bhardwaj <4731196bfa2312dffce2e96e4b970d725db87a47@chromium.org>
Reviewed-by: Daniel Verkamp <72bc170b46ec491f7bdd4359a1c0bfed274de40c@chromium.org>
Commit-Queue: Keiichi Watanabe <815e4e8f7c92a23424d7c3f51ead622bcedbc720@chromium.org>

google/crosvm,google/crosvm,google/crosvm,google/crosvm