Introduce AzureTableStorageSaver as LangGraph Checkpointer

[hienlev]

At the moment there is no official LangChain/LangGraph checkpointer package with Azure Table Storage.

We can add support for it based on existing documentation references:

Azure Tables client library for Python

LangGraph Checkpoint (base classes)

LangGraph Checkpoint MongoDB

LangGraph Checkpoint Postgres

Custom Checkpointer validation tool

[kyleknap]

Van Hien Le (@hienlev) Thanks for reaching out! Official Azure-based LangGraph checkpointers have been on our radar. Could you provide more detail on why you'd prefer Azure Table Storage for the backend of the checkpointer? For example, instead of a CosmosDB-based one o even an Azure Blob Storage-based (assuming it is feasible)?

Also, could you give more detail on what you plan to use the checkpointers for (e.g., human-in-the-loop scenarios, time travel, restore from failed state, etc.)? Any details you can provide would help prioritize the feature request.