Encrypted volume release criteria

[Chris Murphy]

DRAFT 2:

When using the custom partitioning flow, the installer must be able to
correctly interpret, create, and modify any disk containing storage
volumes made from valid ms-dos or gpt disk label partitions; LVM;
LUKS; software RAID sets levels 0, 1 and 5;  ext4, XFS, or Btrfs file
systems to:

## clearly define "storage volume" as any of MBR/GPT partitions, LVM,
LUKS, and RAID sets.


- Create, assign, or delete mount points to/from new and existing
storage volumes
- Assign sizes to newly-created storage volumes
- Remove existing or planned storage volumes
- Reject or disallow invalid disk and volume configurations without crashing

## only change was to remove "and containers" from the 'Remove
existing' bullet, since it's kinda superfluous when "storage volumes"
is already defined. I'd also be OK with "storage containers" vs
"storage volumes", it's sortof a minor distinction.

Chris Murphy