Set attribute (metadata) when storing

[cybercent]

Description

Feature
Currently, the Walrus CLI requires two separate steps to store a blob and then set its attributes.
I’d like to request support for setting attributes at the time of blob creation, ideally using the HTTP API.

Use case
We're uploading images and need to set the content-type and content-disposition attributes for each blob so that we can display images from the aggregator inside web pages.

Docs
Having docs for the metadata module would help other developers better understand and interact with the protocol's on-chain metadata structure.

https://testnet.suivision.xyz/package/0xd84704c17fc870b8764832c535aa6b11f21a95cd6f5bb38a9b07d2cf42220c66

We could, for example, use a PTB to set the metadata for multiple blobs at a time.

Code of Conduct

• I agree to follow this project's Code of Conduct.

[github-actions]

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