feat: Telegram integration

[cvauclair]

• I have looked for existing issues (including closed) about this

Feature Request

Add a Telegram integration crate to easily create Telegram bots from Rig Agents.

Motivation

One of the main use cases of LLMs is to create special purpose chatbots. Although Rig currently provides the building blocks necessary to create chatbots with custom sources of context and tools, Rig is limited in it's support for the deployment of these chatbots. Telegram is a popular chat platform used by many communities which supports bots as first class citizens. It is therefore a natural target for deploying Rig agents.

Proposal

Create a new companion crate rig-telegram which provides a generic telegram bot struct TelegramBot<T: Chat> (name not final). The struct should work for any type that implements the Chat trait defined in rig-core, thus providing an out-of-the-box way for developers to deploy their custom Rig Agents as Telegram bots.

Inspiration / reference

rig-core/cli_chatbot

The companion crate should use the teloxide crate, which provides full Telegram bot API support in Rust.

Alternatives

None considered at this moment.