feat: Implement subscription, add firehose examples

[sugyan]

resolves #11

• Add atrium-xrpc-server member which handles message frames from subscription streams
• Add examples/firehose, it subscribes and prints all texts of posts
  • ref: https://github.com/bluesky-social/feed-generator/blob/main/src/util/subscription.ts
• Update codegen and APIs for these subscription messages

Untitled.mov

[benwis]

Nice work! Are you decoding embeds as well?

[sugyan]

@benwis I've experimented and it seems that the images embed failed to deserialize. I don't know the details, but perhaps I need to implement the deserialization of blobs correctly...
For now, I'd like to leave this problem as a separate issue and finish the work on this branch as a firehose implementation for extracting text.

[benwis]

@benwis I've experimented and it seems that the images embed failed to deserialize. I don't know the details, but perhaps I need to implement the deserialization of blobs correctly... For now, I'd like to leave this problem as a separate issue and finish the work on this branch as a firehose implementation for extracting text.

The reason I ask is because in Bisky we had this weird issue with ciborium where it would fail to parse the internally tagged enum that represented the Embeds.
enarx/ciborium#71

Also, the Blob type is different for the firehose vs non firehose, if I recall one takes a Link map and the other a Byte string.

Perfectly fine to handle this elsewhere, it works well for me!