storage: add Dell Unity and Huawei Dorado backends

[ahmad-can]

No description provided.

[Copilot]

Pull request overview

This PR adds two new Cinder storage backend implementations—Dell Unity and Huawei OceanStor Dorado—to Sunbeam’s storage backend plugin system, along with unit tests and pytest fixtures to validate their configuration models and metadata.

Changes:

• Added DellunityBackend and HuaweiBackend implementations with corresponding StorageBackendConfig subclasses.
• Added unit tests covering backend identity metadata and config validation behavior for both backends.
• Extended the storage backend unit-test fixtures/registry to include the new backend types.

Reviewed changes

Copilot reviewed 5 out of 7 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
sunbeam-python/sunbeam/storage/backends/dellunity/backend.py	New Dell Unity backend + config model.
sunbeam-python/sunbeam/storage/backends/dellunity/init.py	Package initializer for the Dell Unity backend module.
sunbeam-python/sunbeam/storage/backends/huawei/backend.py	New Huawei OceanStor Dorado backend + config model (incl. HyperMetro fields).
sunbeam-python/sunbeam/storage/backends/huawei/init.py	Package initializer for the Huawei backend module.
sunbeam-python/tests/unit/sunbeam/storage/backends/conftest.py	Adds fixtures and registers the new backend classes in the test backend map.
sunbeam-python/tests/unit/sunbeam/storage/backends/test_dellunity.py	New unit tests for Dell Unity backend/config validation.
sunbeam-python/tests/unit/sunbeam/storage/backends/test_huawei.py	New unit tests for Huawei backend/config validation (incl. HyperMetro fields).

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