Keep track of the host output side on virtio-console reset
Keep track of the host output side on virtio-console reset

The previous implementation would lose track of the host output
io::Write stream on receiving a virtio reset request, due to how the
output instance was being passed around through Option instances.

This change replaces one level of Option state with a reference instead,
so the Console instance retains ownership over the output instance and
the virtio-console Worker instance only holds a mutable reference.

Test: Run with a virtio-console device that receives a virtio reset
Bug: b/208540565
Change-Id: Ib672ac244a7209797e1d64feca913b12f31a66d0
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/crosvm/+/3309207
Reviewed-by: Daniel Verkamp <72bc170b46ec491f7bdd4359a1c0bfed274de40c@chromium.org>
Reviewed-by: Chirantan Ekbote <35787c0e27de5c48735e07f8324823b765e8bcbc@chromium.org>
Tested-by: kokoro <2ac7b1f3fa578934c95181d4272be0d3bca00121@google.com>
Commit-Queue: Cody Schuffelen <7618f12f8c1ef40a3c8bf8909fc72185c1ec8ce8@google.com>

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