Write a tool/script to help upgrade projects for compatibility with the latest RGBDS

Many of the changes documented in [`rgbasm-old(5)`](https://rgbds.gbdev.io/docs/rgbasm-old.5) can feasibly be automatically found and edited with a tool like [optimize.py](https://github.com/Rangi42/polishedcrystal/blob/master/utils/optimize.py). Even if regexes only get 80% of the way to compatibility, it should still help and encourage people to update their RGBDS.