Add disk sharing functionality (v35.0) and UUID (v36.0)

[arunmk]

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• This PR adds basic support to create shareable disks. That is done by essentially adding the Shareable field to the Disk structure. Additional other fields such as Encrypted and SharingType, which were added in v35 have also been pulled in. These new fields have been added in v35. If these are not present, the default value is false, i.e., the disks are not shared. If Shareable is set to True, the disk can be attached to multiple VMs. That functionality is provided in VCD 10.2 and does not need any other API change in order to attach to multiple disks. Note that all of the parameters mentioned here are optional, and sensible defaults are mentioned in VCD API to keep them backward compatible. Hence they are specified as omitempty in the API.

• Another UUID parameter was added in v36.0 to help discover the disk that was attached. When a disk is attached to a VM, there is no way to know which of the /dev/sd* devices correspond to the device being attached. However, there is a UUID parameter for each disk available from v36. When the command /lib/udev/scsi_id --page=0x83 --whitelisted --device=</dev/sdX> is run on the VM host, there is a UUID emitted that can be checked against the UUID obtained from the API, and hence the right disk can be discovered. (Note that for the host command to work, the extra option disk.enableUUID must be set on the VM using vmomi).Once the right device /dev/sdx is discovered, the disk can be mounted etc. This parameter is only returned from VCD and hence there is no impact to the callers apart from the additional field in the struct.

• (Optional) @Didainius could you please take a look?

[Didainius]

Sounds quite clear - just if you could improve description of this PR and also add a few lines to CHANGELOG.md.

[lvirbalas]

I'm approving in advance, but as requested by @Didainius we need a proper PR description (which will be commit message too) and an entry in the changelog.

[dataclouder]

I think that we should not add these fields without any function that supports them or tests to make sure the addition doesn't break anything

[lvirbalas]

CSE

[vbauzys]

Last change and we merge this :)