Chat message memory

[kreneskyp]

Implement a memory component that adds TaskLogMessage (chat messages) to the context. Should be implemented as a Langchain memory class and be loadable via config.

There is existing code from Ix v0 agent that queries and loads messages. It may be a partial solution.

[kreneskyp]

Langchain memory was added in #57. A custom memory class or backend should now be possible.