The python toolchain plugin

I will try to extract the python toolchain code from the moon codebase and port it into a python toolchain plugin. I opened this issue only to capture this activity. I also want the new plugin to be able to work with the requirements.txt file in case the uv package manager is declared in its settings. This will be optional, and will not influence the current behavior, but it will allow the user to install dependencies from this file if the project is not entirely ported to use uv.