vhost-device-sound: Add GStreamer audio backend support

[nicholasdezai]

Summary of the PR

Please summarize here why the changes in this PR are needed.

Requirements

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

• All commits in this PR have Signed-Off-By trailers (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.
• All added/changed public-facing functionality has entries in the "Upcoming
  Release" section of CHANGELOG.md (if no such section exists, please create one).
• Any newly added unsafe code is properly documented.

[epilys]

Could you please re-open this PR when it's ready for comments and/or review? We're getting notifications for every change you make, but if we turn off notifications we won't know if it's ready for review or not.

Thanks!

[stefano-garzarella]

@nicholasdezai we really appreciate your effort on adding gstreamer on our vhost-device-sound, but please follow @epilys suggestion.

When you have something that needs reviews (also a draft is fine if there are questions to address), please open the PR, add a good description, and we will be happy to review.

[nicholasdezai]

Thanks for pointing that out! I’ll make sure to do that going forward.

[stefano-garzarella]

Thanks for pointing that out! I’ll make sure to do that going forward.

Great! BTW if you need to run our CI, you can run it locally (https://github.com/rust-vmm/rust-vmm-ci?tab=readme-ov-file#running-the-tests-locally) or just open a PR on your fork.

Also if you need to install something in our container image, you should open a PR on https://github.com/rust-vmm/rust-vmm-container/

[nicholasdezai]

Got it, thanks for the info!