refactor expandWhereReferences to use AST instead of regexp's
validate default_date_range parameter
validate date_field parameter
validate that all sql inputs end with "as <name>", a lot of assumptions this is the case
validate dialect is only bigquery or snowflake
check that alias matches the key name (is this a problem?)
add params to inputs
allow formulas in dimensions like `CONCAT(first_name, ' ', last_name) AS person_name`
also allow jinja expansion like `CONCAT(retailer_url, '{{product_path}}') AS page_url`