This diff adds delivery of the undelivered messages from the database to the client when connecting to the bidirectional stream.
When the client is offline the messages to deliver are stored in the database. Right after the client is online and connected to the messages bidirectional stream we will deliver messages from the database.
The client will process messages and send back processed messages IDs to the Tunnelbroker as [[ https://github.com/CommE2E/comm/blob/efbbde6e7eb567b9a7e1e1bbf4de562a77d2e35a/shared/protos/tunnelbroker.proto#L112 | processedMessages ]] only after that, we will delete messages from the database.
Removing of processed messages implemented in D5584.
Linear task: [[ https://linear.app/comm/issue/ENG-2060/implement-tunnelbroker-grpc-messagesstream-api-handler-in-rust | ENG-2060 ]]