LLM: Add llm subsystem

[Hialus]

Very rough draft for early review

Motivation

For Pyris V2 we need a robust and extendable subsystem for handling LLMs. This system will support different LLM selection strategies in the future, which are all accessible through the same Interface.

Description

Class Diagram:

Explanation:

• The RequestHandlerInterface is the entrypoint / Facade for the entire subsystem
• The BasicRequestHandler is the first simple implementation of it, which simply forwards to one specified LLM
• In the future different request handlers would implement different logic for switching between multiple LLMs
• An IrisMessage is our own message format, which we can then convert to/from e.g. Langchain messages
  • Currently only has role and text, but in the near future also supports images and possibly more
• The LlmManager is a singleton, which stores/handles all the different LLMs
• The different LlmWrapperInterfaces and their implementations are the direct connection to the LLMs and handle any vendor specific logic (i.e. converting messages)

There is also the follow up #52 to improve the config file parsing

[kaancayli]

Looks good to me. LGTM

[yassinsws]

For Futur's work, maybe change the model to enum

[Hialus]

For Futur's work, maybe change the model to enum

This is not possible, as it is an identifier from a config fille. The model identifier is therefore dynamic

[yassinsws]

Looks good to me for a first Version, approved !