Add query optimization

[michaelmior]

The tool could also be useful for explaining some simple query optimizations. For example, pushing a filter through a join. This would probably best take the form of a series of optimization rules which can be toggled on and off with some clear way to see how the expression changes.

[michaelmior]

First pass of optimization is in #1657.

Future useful optimizations could involve join order selection and others.

[michaelmior]

SQLGlot has a good list of other possible optimizations.