SQL logic test suite

[nukep]

To guarantee that SQL queries actually do as they're told, a very thorough test suite needs to be added.

Sqllogictest may be worth looking into: https://www.sqlite.org/sqllogictest/doc/trunk/about.wiki

[acmiyaguchi]

I'll be committing a bit of time to get some sort of test suite running. I'd like to be able to hack on this have the confidence that my changes aren't creating any major regressions.