WIP, but main extractor paths seem to work

This adds a possible macro for building JDBC type sources.

Right now just a size annotation, also might need an unsigned one.

Number of types available probably needs to increase. But it seems to build most of the info we would need for a source
It doesn't compile the way i've set that up. I'll need to add some tests like the bijection magic one for missing implicit to show the cases that shoudln't work