Support ORDER BY ALL for projected expressions

[osipovartem]

Which issue does this PR close?

Closes a planner gap where ORDER BY ALL only accepted raw column projections and was silently ignored for set-operation outputs.

Rationale for this change

ORDER BY ALL means sorting by every output column in select-list order. Expanding it to the equivalent 1-based ordinal keys supports computed expressions, aliases, aggregate outputs, wildcard-expanded projections, and set-operation outputs through one planner path.

The ordinal expansion also sorts already-projected columns rather than evaluating computed expressions again. Physical execution remains on DataFusion's existing vectorized SortExec; this adds no row-wise conversion or custom physical operator.

What changes are included?

• expand OrderByKind::All to ordinal OrderByExprs from the output width
• provide output width for non-SELECT set expressions instead of dropping ORDER BY ALL
• add focused execution coverage for computed expressions, null-order options, set operations, and aggregate output

Are these changes tested?

• cargo +1.95.0 test -p datafusion-sqllogictest --test sqllogictests -- order_by_all.slt --test-threads 1
• cargo +1.95.0 test -p datafusion-sql --test sql_integration -- --test-threads 8 (591 passed)
• cargo +1.95.0 clippy -p datafusion-sql --all-targets -- -D warnings
• cargo +1.95.0 fmt --all -- --check

Snowflake dialect parsing support is proposed independently in apache/datafusion-sqlparser-rs#2502; this planner change is generic to every dialect that already emits OrderByKind::All.

[codecov-commenter]

Codecov Report

❌ Patch coverage is 89.47368% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 81.94%. Comparing base (6079a1e) to head (b5fedbc).
⚠️ Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
datafusion/sql/src/query.rs	89.47%	1 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #25243      +/-   ##
==========================================
- Coverage   81.95%   81.94%   -0.01%     
==========================================
  Files        1133     1133              
  Lines      423799   423793       -6     
  Branches   423799   423793       -6     
==========================================
- Hits       347307   347294      -13     
- Misses      55899    55907       +8     
+ Partials    20593    20592       -1     

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[jayzhan211]

Thanks @osipovartem , LGTM!

[jayzhan211]

It would be nice to add

SELECT b AS a, a AS b FROM t ORDER BY ALL, plus optionally a self-join with duplicate output names.