Splitting targets for ag2, autogen 0.2.x and autogen 0.4.x runtimes

[davorrunje]

Autogen is splitting into two separate repositories and will continue releasing mutually incompatible packages. Moreover, they will both use the same top-level module autogen making them incompatible in the same Python environment. The solutions for this is to create separate package targets ag2, autogen and autogen-04dev that will depend on ag2 (versions 0.3.x), autogen (versions 0.2.x) or autogen-agentchat (version 0.4.0-devX). We also need to create dev containers for each of the runtime used.