Host companions on Steamship

[EniasCailliau]

🥞 This PR depends on #49, since GH doesn't support stacked PRs across repos I recommend we merge that PR before we have a look at this one.

This PR introduces the ability to create your own AI companion on Steamship. To simplify the setup process, I added a ready-to-use ai-companion package. This package is hosted on the a16z account on Steamship and is publicly available so everyone can spawn their own instance of the package.

With this PR, users now have the tools necessary to create their own unique AI companion on the Steamship platform.

A follow-up PR will provide optional scaffolding to allow users to modify and personalize their AI companion backend stack.