Storage Partitioned Transfer Base

[jaschrep-msft]

Implements two foundation components to implement partitioned upload and copy.

• PartitionedStream: Consumes a Box<dyn SeekableStream> and converts it to a Stream<Item = Result<Bytes, Error>> where each Ok(Bytes) returned is a contiguously buffered partition to be used for a put block or equivalent request.
• run_all_with_concurrency_limit(): Takes a sequence of async jobs (impl FnOnce() -> impl Future<Output = Result<(), Error>>). These will be sequences of put block operations or equivalent requests.

[Copilot]

Pull Request Overview

This PR implements foundational components for partitioned upload and copy operations in Azure Storage Blob SDK, introducing stream partitioning and concurrent operation execution capabilities.

• Adds PartitionedStream that converts a SeekableStream into partitioned Bytes chunks for block operations
• Implements run_all_with_concurrency_limit() for executing async operations with configurable concurrency
• Includes comprehensive test coverage for both components

Reviewed Changes

Copilot reviewed 5 out of 6 changed files in this pull request and generated 16 comments.

Show a summary per file

File	Description
sdk/storage/azure_storage_blob/src/streams/partitioned_stream.rs	New implementation of PartitionedStream with Stream and FusedStream traits, plus test suite
sdk/storage/azure_storage_blob/src/streams/mod.rs	Module declaration for streams
sdk/storage/azure_storage_blob/src/partitioned_transfer/mod.rs	New implementation of run_all_with_concurrency_limit() with concurrency control logic and tests
sdk/storage/azure_storage_blob/src/lib.rs	Module declarations for new partitioned_transfer and streams modules
sdk/storage/azure_storage_blob/Cargo.toml	Added bytes and futures dependencies (and rand for tests)
Cargo.lock	Lock file updates reflecting new dependencies

[github-actions]

API Change Check

APIView identified API level changes in this PR and created the following API reviews

azure_storage_blob

[jaschrep-msft]

@heaths I think this is pretty stable now that your core comments are addressed. Can I get another review on this?

[heaths]

I will, but in general I was letting your team sign off on the rest of the changes and Storage PRs in general. I've only been taking a peek more recently since your team has been much more comfortable with Rust. I'm mainly just looking at more architectural concerns. But you can always mention me specifically in reviews or contact me offline too.