Feature Request: Create Subvolume for BTRFS Filesystems in Installer

[ElliotLurie]

Hello, when installing Void Linux with a BTRFS root partition, no subvolumes are created. Having a subvolume is standard for most distributions (usually named @) and helps with snapshotting with utilities like timeshift.

[ElliotLurie]

I created a fork here that implements this feature in a basic manner. However, BTRFS would very much benefit from zstd compression, so I could add that as well if only that were added to the dependencies of base-voidstrap or even btrfs-progs.