fn get_boot_dir_for_grub(physical_root: &Dir) -> Result<(Dir, Utf8PathBuf)>Expand description
Find the directory holding GRUB’s configuration and the BLS entries on a booted system, returning it and its absolute path.
This is /sysroot/boot, unless there’s a separate boot partition, which
is mounted on /boot. How it gets mounted there varies: bootc install
adds a systemd.mount-extra karg, but other tools may use e.g. an fstab
entry instead. Everything that reads or writes GRUB’s boot entries must go
through this, via Storage::require_boot_dir or
Storage::require_grub_boot_path.