Use an explicit source in program.test.ts

[philrz]

In contemplating #3218, @nwt remarked:

This ultimately traces back to the change we made to the HTTP API to ignore the pool name zui sends along side a query. That pool was treated as a default source if the query didn't include an explicit source. Without it, you get the null source. And with type checking against the null source instead of a pool, you get errors.

Therefore in this branch I've added explicit leading from test to the queries, which gets the tests to pass again with the newer SuperDB dependency.

Closes #3218