add the ability to run sqlpage functions with dynamic contents instead of just literal values

[lovasoa]

Today, the following is not supported:

select sqlpage.some_function(my_column) from my_table

It fails with an error saying something like some_function(my_column) is not a valid call. Expected a literal single quoted string..

This is because sqlpage runs all functions before sending the query to the database.

With some engineering, it should be possible to support running the function either before or after the query has run, depending on context, which would be very powerful.

[matthewlarkin]

This looks promising! 💪