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/tasks/main.yaml

@@ -0,0 +1,30 @@
+---
+- name: Ensure btrfs ROOT layout
+  community.general.btrfs_subvolume:
+    name: "/{{ item.subvol }}"
+    # filesystem_device: /dev/sdb1
+    # fileystem_label: btrfs-root # only 1 of the 3 required
+    filesystem_uuid: "{{ item.uuid }}"
+  loop: "{{ btrfs_mounts }}"
+  become: true
+
+- name: Ensure fstab contains btrfs mount entries
+  ansible.posix.mount:
+    path: "{{ item.path }}"
+    src: "UUID={{ item.uuid }}"
+    fstype: btrfs
+    opts: "{{ item.opts }},subvol={{ item.subvol }}"
+    state: present
+  loop: "{{ btrfs_mounts }}"
+  become: true
+  notify: Reboot machine
+
+- name: Ensure external HDD is mounted
+  ansible.posix.mount:
+    path: /mnt/ext
+    src: "UUID=01b221f2-83a5-49e4-bdef-ee9ee9ac5310"
+    fstype: ext4
+    opts: "noatime"
+    state: present
+  become: true
+  when: "should_mount_external_hdd"