Add file upload/extension support in .yaml

[developer-gliu]

Currently in the UI, I need to pass in files into the agents (.pkl and .txt) into the query in order to have the necessary context; so something like this.

We need to add functionality to be able to do this through the .yaml file so that we can directly go through the terminal and call all the agents sequentially without the need for the UI.

Not sure if this should be in POC0/1.

[psschwei]

For now, to handle passing files between agents we should create a working directory for each run (say, /tmp/weather-job/run_234r2342) and assume all agents can read/write in that directory.