This adds the capabilities to stream messages for GitLab Duo chat.
The streamed chunks get send over aiCompletionResponse but the order
is not guaranteed on the client. Each chunk has a chunkId which has a
guaranteed order, starting with 1.
The client_subscription_id is meant for the client to identify which
mutation belongs to which subscription response. However, chat is a
special feature where we want to sync responses between multiple chat
instances of the same user.
This means we want to have two different subscriptions for the same
request:
1. User-specific to sync between multiple clients
2. Request-specific for streaming
By not streaming the response when a client_subscription_id is not
present, we also make sure that older clients still work when the
stream_gitlab_duo is enabled. Otherwise, they would receive a streamed
response on a subscription on user_id and resource_id.
Checkout !130415 (closed) as it combines this MR with the FE changes and updates the GraphQL subscriptions
MR acceptance checklist
This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.
