Investigate common abstractions when lowering from an automatic layout system to HEIR

The goal is to find common abstractions that can be used when building a pipeline from an automatic layout system (e.g., Rotom) to HEIR.

Ideas discussed during 6/16 office hours:
- Explore a seamless way to pass input data (i.e., numpy arrays in Rotom) and layout metadata from Rotom to HEIR.
- Explore lowering Rotom's layout notation to HEIR's layout notation.
- Build a pipeline from Rotom python backend to heir_py (heir python).