Use sqlglot to parse queries to insert select literals

[ccharlesgb]

Description

This PR integrates the parser sqlglot into the dry runner to transform dbt models and insert select literals

Using a parser could be quite risky because the dry runner is now converting dbt SQL to and from an abstract syntax tree so we are relying on sqlglot to be able to handle all cases without changing the query of dbt models.

Fixes #11

Checklist:

• [x] I have run make verify and fixed any linting or test errors
• [x] I have added appropriate unit tests or if applicable an integration test
• [x] OPTIONAL: I have run make integration against a Big Query instance