Fun: `graphile-export` can simplify some pg-sql2 expressions

[benjie]

We do a number of optimizations in graphile-export... I just noticed another that we could do would be compressing SQL expressions. For example:

fragment: sql`${alias}.${sql.identifier("type")}`

could easily become:

fragment: sql`${alias}."type"`

or if we're being really fancy:

fragment: sql`${alias}.type`

Wouldn't make a huge difference to performance, but is much easier for humans to read (which is one of the goals of Graphile Export!)