nf-azure: support Microsoft Fabric OneLake as object storage

New feature

nf-azure maps az://container/path to https://{account}.blob.core.windows.net. OneLake uses a different endpoint (https://onelake.dfs.fabric.microsoft.com, account onelake) and path layout (workspace / lakehouse / Files/). There is currently no way to use OneLake as workDir or for channel files.

Use case

Run pipelines with Azure Batch + Fusion + Entra managed identity, storing work and data in a Fabric lakehouse instead of a classic Blob container.

URI mapping: account = onelake, container = workspace, blob path = {item}.lakehouse/Files/{path}.

    workDir = 'az://my-workspace/my-lakehouse.lakehouse/Files/nf-work'

Fabric constraints: Entra-only auth, lakehouse must already exist, I/O under Files/, GUIDs if names contain spaces.

Suggested implementation

Extend nf-azure (not a new plugin). Make the storage endpoint configurable (see #6580) and add azure.storage.kind = 'onelake' to translate az://workspace/item.lakehouse/Files/... to the OneLake URL, then pass that endpoint through to Fusion. Spike Blob SDK + managed identity against a real lakehouse first.

Start by reviewing nf-azure's existing storage path and issue #6580, then spike Blob SDK access with Entra managed identity against a real Fabric lakehouse. Verify the OneLake URI mapping, endpoint configuration, and Fusion handoff for workDir and channel files. Done means an existing lakehouse can be used under the stated Files/ and naming constraints.