Create mount points in fs_init() if they don't exist

[aanderse]

In containerized or virtualized environments, standard mount point directories may not exist at boot. Ensure they are created before attempting to mount.

---

when running finix in a container we can skip stage 1 (initramfs) entirely - this change let's me boot directly into finit in my stage 2 without the need for a shell script to mkdir and then call finit! 🚀