Cinder driver for the InfoScale Storage cluster

Introducing a new Cinder driver for the InfoScale Storage cluster.

The driver will expose File-as-LUN capabilities, enabling Cinder to provision and manage block storage backed by file by InfoScale Cluster Filesystem (CFS). This will implement all the minimum Cinder features and implemented via REST APIs to the InfoScale cluster.

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Proposed Change
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1. Introducing a new driver in cinder/volume/drivers/infoscale.py
2. Implement standard Cinder volume operations by translating them to InfoScale cluster REST API calls.
3. Support File as LUN workflow: files on the cluster are exported as block devices via Cinder.
4. Add configuration options for endpoint URL, authentication, pool/namespace, etc.
5. Driver will comply with Cinder driver interfaces (create_volume, delete_volume, extend_volume, create_snapshot, etc.)

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Cross-project Impact
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This feature requires changes in:

os-brick: To add new connector logic for InfoScale Cinder volumes.
Nova: To consume the os-brick connector and attach/detach volumes provisioned by the InfoScale Cinder driver.

Separate blueprints will be proposed in the respective projects.