Support for dollar-quoted strings

[Vedin]

There is an errors in dbt-gitlab with: 000200: SQL error: ParserError("Expected: literal string, found: $$Base model for metadata about test executions. One row per node per run.$$ at Line: 2, Column: 50") Snowflake happily accepts dollar-quoted strings. So we need to support something like this as literal: $$Some text here$$