Check PVE

Features:

• ZFS fragmentation checks
• Support PVE API tokens

Features:

• basic monitoring of ceph cluster
• services: check if service is enabled (PVE 7.x)
• storage: show name in check output
• disk-health: distinguish between unknown status and failed disks

Fixes:

• disk-health: list disks properly
• code cleanup

Breaking changes: Please note that this release will require Python 3