add newline around model SQL in incremental materialization

[drewbanin]

Issue

Issue description

A change to the incremental materialization code in 0.11.0 causes incremental models to fail if the last line of the model contains a comment: fa43d9d

This change puts the closing paren for the incremental subquery on the same line as the model itself, so line comments will also comment out our closing paren.

Instead, this code should happen on three different lines. Let's add a test for this just in case, as it's a very easy thing to miss. In general, we should be more mindful of interpolating sql on the same line as materialization code.

System information

0.11.x

Steps to reproduce

Run this model code:

{{ config(materialized='incremental', sql_where='true') }}

select
  1 as id -- a closing paren will be injected at the end of this comment

[drewbanin]

fixed in #1019