feat(sql): plan MINUS as EXCEPT

[osipovartem]

Summary

• plan the SQL MINUS set operator through the existing EXCEPT logical plan
• support the same quantifiers already accepted by the parser
• add a Snowflake-dialect integration test that protects the resulting anti-join plan

Performance

This is a planner alias only. MINUS reuses the existing vectorized EXCEPT physical path and introduces no new operator or per-row conversion.

Validation

• cargo +1.95.0 test -p datafusion-sql --test sql_integration (600 passed)
• cargo +1.95.0 clippy -p datafusion-sql --all-targets -- -D warnings
• cargo +1.95.0 fmt --all -- --check
• git diff --check