Add PK constraint on bigserial ID columns on postgres adapter (needs feedback)

In #10410 it seems that only the default (serial) and UUID type ID's are supported in master. This is a regression from being able to successfully use the 64bit integer brother of serial named bigserial.

I was able to find one way to stop the regression. I'm somewhat confident that this isn't the true fix to #10410 though as:
 * This will continue to break as people require PK's of different types
 * I believe this is pretty much a complete hack

I just wanted to chuck it out there and hope that someone more familiar can pick up where my limited knowledge left off. Who's the right person to look at this?