Remove the call to render() in the statement macro

[drewbanin]

Describe the bug

dbt currently calls render() on already-compiled SQL in statement blocks. This render usually is a no-op -- if the SQL is already compiled, then calling render() on it should be a no-op. Sometimes though, compiled code contains valid jinja statements. This can happen if:

• the source code contains a {% raw %} block
• a user-supplied configuration is provided which contains uncompiled jinja code (the culprit in this issue)

Steps To Reproduce

Given a model like:

-- models/debug.sql

{% raw %}
select '{{ 1 + 1 }}' as debug
{% endraw %}

The resulting query that dbt runs should be:

create view "analytics"."demo_schema"."debug__dbt_tmp" as (
  select '{{ 1 + 1 }}' as debug
);

Instead, it is:

create view "analytics"."demo_schema"."debug__dbt_tmp" as (
  select '2' as debug
);

System information

This bug affects all supported database. It was reproduced on 0.14.0 and later, but this particular line of code has existed in dbt for quite a bit longer than that.