Add support for custom container registry in langgraph CLI

[hyunho1027]

Hello,

I am an experienced developer currently working on implementing an agent server using the langgraph open source project. However, in my development environment, accessing public container registries like DockerHub is difficult. To address this, I would like to contribute a new feature to the langgraph CLI that allows users to specify a custom container registry via an option in the langgraph up command.

Proposed Feature:

Add an option to the langgraph up (also langgraph dockerfile) CLI command that allows users to specify a custom container registry.
Modify the command to pull images from the specified registry instead of defaulting to DockerHub.
Example Usage:

$ langgraph up --registry my.custom.registry.com

Benefits:

This feature will enable users in restricted environments to utilize langgraph without relying on public container registries.
It will add flexibility for users who prefer or need to use private or internal registries.
I am happy to work on this feature and submit a pull request once the issue is reviewed and approved. Please let me know if you have any questions or additional requirements.

Thank you!

[hyunho1027]

I have implemented the code to resolve this issue. Please review it and confirm.

hyunho1027@717c1e2