feat: Set up filesystems

Automatically set up btrfs root and data filesystem, as well as external
HDD.

This automation change assumes a layout exactly as in current bob to
function by default, can be changed to any btrfs layout with the
`btrfs_mounts` configuration option, however.

roles/filesystem/handlers/main.yaml

@@ -0,0 +1,7 @@
+---
+
+- name: Reboot machine
+  ansible.builtin.reboot:
+    connect_timeout: 600
+    post_reboot_delay: 10
+  when: "should_reboot_machine"