Enable features required for tests

[tedinski]

Summary of the PR

cargo test works, but due to how cargo enables features for crates built in a workspace, this is by accident, and the following commands fail without this patch:

• Fixes cargo test -p virtio-console
• Fixes cargo test -p virtio-queue-ser

These changes are modeled after the dev-dependencies that already exist to enable these features in e.g. virtio-vsock:

https://github.com/rust-vmm/vm-virtio/blob/c527b45dada0a81d343aca7f06759d5637d6429a/crates/devices/virtio-vsock/Cargo.toml#L18-L20

Requirements

Before submitting your PR, please make sure you addressed the following requirements:

• [x] All commits in this PR are signed (with git commit -s), and the commit message has max 60 characters for the summary and max 75 characters for each description line.
• [ ] All added/changed functionality has a corresponding unit/integration test.
• [n/a] All added/changed public-facing functionality has entries in the "Upcoming Release" section of CHANGELOG.md (if no such section exists, please create one).
• [n/a] Any newly added unsafe code is properly documented.

[andreeaflorescu]

We are experiencing some problems with the CI. This PR doesn't change anything that could impact fuzzing, so we can merge the PR without the test passing.