[Refactor] Query Formatter Test Case Fixes

[colinthebomb1]

Overview

This PR updates the query formatter logic to support more complex test cases. All existing test cases now pass.

TODOs

Add UNION test cases and support them in formatter

[Copilot]

Pull request overview

This PR expands QueryFormatter’s AST→mo_sql_parsing JSON conversion to cover additional SQL constructs so previously-disabled formatter test cases can be asserted again.

Changes:

• Re-enabled many tests/test_query_formatter.py assertions by comparing formatted SQL vs expected queries via mo_sql_parsing.parse().
• Enhanced core/query_formatter.py to support SELECT DISTINCT, DISTINCT ON, subqueries in FROM/JOIN, NULL/IS NULL, CASE, IN lists, arithmetic operators, and INTERVAL.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
tests/test_query_formatter.py	Uncomments/enables formatter assertions across many query fixtures.
core/query_formatter.py	Adds/adjusts formatting logic for DISTINCT, DISTINCT ON, subquery sources, more operators/expressions, and interval handling.

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[baiqiushi]

LGTM.

[HazelYuAhiru]

Overall LGTM