Inventorize disks in eryph storage independently of catlets

[ChristopherMann]

Currently, the inventory job only detects virtual disks (VHDs) which are attached to VMs. We should extend the inventory job such that it scans the file system for VHD files and inventorizes them. This way, we can pick up virtual disks which were manually added by the user or rediscover unattached disks which we lost track of.

The inventory job should regularly scan all file system paths which were configured as storage in eryph. We need to keep in mind that some of the file systems might be clustered and might be visible to multiple hosts which are managed by eryph. Hence, we should either:

• use mechanism to define a primary host for each shared file system. The primary host is then responsible for scanning the file system and sending inventory updates.
• use a mechanism to identity events of different hosts which reference the same file system or virtual disk and deduplicate them.

AB#678

[fw2568]

Note that currently all disks attached to any type of VM (not just catlets) are inventorized. This is inconsistent with the inventorization behavior since we do not import non-catlet VMs. Instead, after this change, disks that are either in storage or attached to a catlet should be imported.