feat(storage): initial config support for LVM

[joseivanlopez]

Add support to the storage config for creating LVM volume groups, logical volumes, thin pools and thin logical volumes. Reusing volume groups or logical volumes is out of the scope of this PR. The schema for volume groups is defined according to the auto_storage documentation.

  "storage": {
    "drives": [
      ...
    ],
    "volumeGroups": [
      ...
    ]
  }

[coveralls]

coverage: 71.702%. remained the same
when pulling f640f2d on joseivanlopez:storage-lvm
into af3c4f6 on openSUSE:master.

[joseivanlopez]

Note for reviewers: preferably review commit by commit to easily follow all the changes.

[ancorgs]

I only have a question about the example. Other than that, this looks to me like a nice step forward. Approved!