images without a default partition table still require --rootfs even when specified in customizations.disk

[ondrejbudai]

$ cat config.toml
[[customization.disk.partitions]]
type = "lvm"
name = "mainvg"

[[customization.disk.partitions.logical_volumes]]
name = "rootlv"
mountpoint = "/"
label = "root"
fs_type = "ext4"
minsize = "10 GiB"

[[customization.disk.partitions.logical_volumes]]
name = "swaplv"
fs_type = "swap"
minsize = "1 GiB"

$ podman run --rm --privileged --security-opt label=disable -it -v /var/lib/containers/storage:/var/lib/containers/storage --pull=newer -v ./config.toml:/config.toml quay.io/centos-bootc/bootc-image-builder --local --type raw quay.io/fedora/fedora-bootc
error: cannot build manifest: no default root filesystem type specified in container, please use "--rootfs" to set manually