datavol: Add support for LVM

The `datavol.yml` playbook can now create LVM volume groups and logical
volumes.  This will be useful for physical hosts with static storage.

LVM LVs and VGs are defined using the `logical_volumes` Ansible
variable, which contains a mapping of VG names to their properties.
Each VG must have two properties: `pvs`, which is a list of LVM physical
volumes to add to the VG, and `lvs`, a list of LVs and their properties,
including `name` and `size.  For example:

```yaml
logical_volumes:
  kubernetes:
    pvs:
    - /dev/nvme0n1
    lvs:
    - name: containers
      size: 64G
    - name: kubelet
      size: 32G
```

datavol.yml

@@ -21,6 +21,28 @@
     tags:
     - install
 
+  - name: ensure lvm volume groups exist
+    lvg:
+      vg: '{{ item.key }}'
+      pvs: '{{ item.value.pvs }}'
+    loop: '{{ logical_volumes | d({}) | dict2items }}'
+    loop_control:
+      label: '{{ item.key }}'
+    tags:
+    - lvm
+    - lvm-vg
+  - name: ensure lvm logical volumes exist
+    lvol:
+      lv: '{{ item.1.name }}'
+      vg: '{{ item.0.key }}'
+      size: '{{ item.1.size }}'
+    loop: '{{ logical_volumes | dict2items | subelements("value.lvs") }}'
+    loop_control:
+      label: '{{ item.0.key }}/{{ item.1.name }}'
+    tags:
+    - lvm
+    - lvm-lv
+
   - name: ensure data volume filesystem exists
     filesystem:
       dev: '{{ item.dev }}'