add deps for audio firmware and device-specific setup

[classabbyamp]

• linux-firmware: add dependencies on sof-firmware and alsa-firmware
• alsa-lib: depend on alsa-ucm-conf

[baylinux01]

First of all, thank you so much for taking the time to look into my original issue and putting together this PR.
I really appreciate the quick action to help solve the audio problem.
I have a small suggestion regarding the implementation, though I completely understand if there are backend constraints I'm not aware of from a maintainer's perspective.
My only worry with adding sof-firmware as a hard dependency to linux-firmware (or linux-base) is the impact on the base system. Since Void is so well-regarded for its minimal nature, making this a mandatory package means it will be pulled in on systems that might not actually need it. For instance, servers, headless setups, or systems with older audio chipsets would be carrying this firmware unnecessarily, which slightly goes against that lean philosophy.
Because the main pain point was not having sound during the initial live session and testing phase, I was wondering if it might make more sense to handle this outside of the core dependencies. For example:
-Including it directly in the live ISO: If sof-firmware were added to the void-live manifest, users would have working sound out-of-the-box when booting the ISO. This makes for a much better first impression without affecting the actual installed base system.
or
-An optional installer step: Alternatively, perhaps an 'Install additional firmware' checkbox in void-installer (which could include things like sof-firmware, b43-firmware, etc.) would allow users to opt-in if they know their hardware needs it.
I just wanted to throw these ideas out there as a potential alternative path. I'm not sure how complex either of those would be to implement in the build system, but I'd love to hear your thoughts on it!

[classabbyamp]

void is not minimal and not intended to be minimal.

users can use ignorepkg to remove the package if they so choose.