Yield SQLUpdates more efficiently

[Lambdanaut]

In the new templates, we have a lot of functions that return SQLUpdate
however, one of the main benefits to moving to the coroutine model was to avoid ever having to return SQLUpdate anywhere (it's an anti-pattern!).

We should instead just yield whenever necessary to get the DB query executed right away (which we couldn't do in Paima v1)

For functions that only execute a single query, this will be simple, however for functions that execute multiple queries, we'll need to break it apart to yield the SQLUpdates at the appropriate times.

Example of function that returns SQLUpdate at the end: