Conditions in the Built-in Audits dont support macro vars #2399

Slack context: https://tobiko-data.slack.com/archives/C044BRE5W4S/p1712179233739539

Built-in audits (such as unique_values) have a condition property that can be used to pass extra conditions like so:

@MODEL (
   ...
  audits (
    unique_values(columns=(id), condition=foo='bar')
  )
)

However, if you want to use @start_dt and @end_dt in the condition to limit the amount of data scanned on the underlying engine, they dont expand out correctly.

For example, this condition fails:

condition=ts between @start_dt and @end_dt

-- ValueError: Unsupported expression type MacroVar

You can wrap it in @SQL to get further:

condition=@SQL('ts between @start_dt and @end_dt')

-- sqlglot.errors.ParseError: Invalid expression / Unexpected token. Line 1, Col: 38.
  ts between 2023-03-01 00:00:00+00:00 and 2023-03-10 23:59:59.999999+00:00
Error: Failed to resolve macro for expression. Error trying to eval macro.

Generated code: self.parse_one(self.template('ts between @start_dt and @end_dt', locals()))

Original sql: @SQL('ts between @start_dt and @end_dt') at '.'

It seems that it doesn't take the current dialect into account and just does a string substitution. That same expression in a normal model would correctly expand to CAST('@start_dt' AS TIMESTAMP) AND CAST('@end_dt' AS TIMESTAMP)

You can work around the dialect issue by writing SQL to convert the string values to timestamps:

condition=@SQL('ts between cast(''@start_dt'' as timestamp) and cast(''@end_dt'' as timestamp)')

However, that's a bit hacky. It would be good if the rules for the model SQL dialect were applied