virtio: video: use thiserror in the command module
virtio: video: use thiserror in the command module

This reduces the code a little bit.

BUG=b:161774071
TEST=arc.VideoDecodeAccel.h264_vm passes on hatch
TEST=arc.VideoEncodeAccel.h264_360p_i420_vm passes on hatch

Change-Id: I547d0d26a1a69bc50af4df9b6bb2b4016ff760c6
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/crosvm/+/2983089
Tested-by: kokoro <2ac7b1f3fa578934c95181d4272be0d3bca00121@google.com>
Commit-Queue: Alexandre Courbot <301cd6a3ea50a894b4b51e385c5eb12b9a4ffc0c@chromium.org>
Auto-Submit: Alexandre Courbot <301cd6a3ea50a894b4b51e385c5eb12b9a4ffc0c@chromium.org>
Reviewed-by: Keiichi Watanabe <815e4e8f7c92a23424d7c3f51ead622bcedbc720@chromium.org>
Reviewed-by: David Staessens <a4557d4b9b905b8f9d5c87334b8d9f562e1ec119@chromium.org>

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