Datastore support for NVRAM volumes

[rsmontero]

Description NVRAM is a storage medium used to persist UEFI variables. These variables are used by the OS to store different configuration attributes.

In general, this information can be associated to a guest and it should be able to offer the same persistence attributes of disk images.

This issue is to integrate NVRAM creation and management into the storage subsystem either:

• Using a special DISK
• Using the Files & Kernels datastore

Use case Persist changes to NVRAM variables when a VM is terminated.

Interface Changes This will require new template attributes, Sunstone options to select existing NVRAM variables, and Datastore/Image template changes.

Additional Context Created from conversation in issue #2481

Progress Status

• [ ] Branch created
• [ ] Code committed to development branch
• [ ] Testing - QA
• [ ] Documentation
• [ ] Release notes - resolved issues, compatibility, known issues
• [ ] Code committed to upstream release/hotfix branches
• [ ] Documentation committed to upstream release/hotfix branches