fix(bigquery): translate EXTRACT(DOW/DOY) case-insensitively for SQL API

[tlangton3]

Summary

Fixes #10644. When querying via the SQL API (Postgres wire protocol), EXTRACT(DOW FROM column) (and EXTRACT(DOY FROM column)) fail on BigQuery with:

A valid date part name is required but found dow

This pattern originates from Tableau connecting via the SQL API.

Changes

• Override the extract expression template in BigqueryQuery.ts to use date_part|upper for the DOW/DOY comparisons, matching the existing DATETRUNC template's case-insensitive convention
• Add an integration test that exercises EXTRACT(DOW FROM column) against BigQuery
• Add an MSSQL skip for the new test (MSSQL has no EXTRACT builtin)

Implementation Details

The BigQuery extract template uses a Jinja if to translate Postgres-style DOW/DOY date parts to BigQuery's DAYOFWEEK/DAYOFYEAR:

'EXTRACT({% if date_part == \'DOW\' %}DAYOFWEEK{% elif date_part == \'DOY\' %}DAYOFYEAR{% else %}{{ date_part }}{% endif %} FROM {{ expr }})'

The comparisons are case-sensitive. DataFusion can pass date_part as lowercase 'dow', causing the if to fall through to {{ date_part }} and emit EXTRACT(dow FROM ...) — which BigQuery rejects.

The fix adds the |upper filter to both comparisons:

'EXTRACT({% if date_part|upper == \'DOW\' %}DAYOFWEEK{% elif date_part|upper == \'DOY\' %}DAYOFYEAR{% else %}{{ date_part }}{% endif %} FROM {{ expr }})'

This mirrors the existing templates.functions.DATETRUNC template which already correctly uses date_part|upper == 'WEEK'.

Why simple EXTRACT(DOW FROM CURRENT_DATE) cases work without the fix

DataFusion's ConstEvaluator constant-folds EXTRACT(DOW FROM CURRENT_DATE) to an integer literal at plan time (CURRENT_DATE is a Stable UDF). The folded integer is sent to BigQuery — the template is never invoked. Only EXTRACT(DOW FROM column_reference) (and similar non-foldable cases) reach the template and trigger the bug.

Testing

• Reproduced the bug locally against live BigQuery before applying the fix (same error as in the issue)
• After fix: integration test SQL API: EXTRACT DOW from column reference in SQL push down passes
• Full BigQuery integration suite with Tesseract ON: 103 passed, 2 pre-existing failures (SQL API: ungrouped pre-agg and Tesseract: SQL API: Timeshift measure from cube), no regressions
• TypeScript compilation passes

Linear Ticket

N/A