Multi remote attachment content type

[cameronvoell]

Related to https://github.com/xmtp/XIPs/blob/main/XIPs/xip-50-multiple-remote-attachments-content-type.md

Todo:

• set proto branch back to main when feat: new multi remote attachment content type proto#243 is merged

[nplasterer]

Will we need to write these codecs in Kotlin and Swift now too? Or do they live entirely in Rust? Assuming we will still need to for registering the codecs on the client?

[cameronvoell]

Will we need to write these codecs in Kotlin and Swift now too? Or do they live entirely in Rust? Assuming we will still need to for registering the codecs on the client?

@nplasterer We still need to have Codec classes in Kotlin + Swift, but we can borrow the encode/decode logic from rust which sort of enforces a contract on how the data is represented, which roots back to the proto repo. So this is moderately better than the JSON types which you had to write more "manual" parsing for.