Add SQL APPLY constructs - #13539

Fixes #5133.

This adds first-class CROSS APPLY and OUTER APPLY support without changing
the meaning of the existing LATERAL construct.

The new Apply object follows the lateral selectable topology and is exposed
through cross_apply() / outer_apply() constructors and corresponding
selectable methods. APPLY targets retain lateral correlation, participate in
cache-key traversal, and render as the right side of a join without an ON
clause. Direct Select inputs are coerced to subqueries, and incompatible join
criteria or join flags raise an explicit argument error.

The change includes public exports, API and tutorial documentation, an
unreleased changelog entry, and coverage for correlation, constructor and
method forms, direct Select coercion, join validation, cache-key differences,
FROM linting, and SQL Server compilation.

Validation:

• Added 6 focused APPLY test cases; these are included in the suite totals below
• full SQLAlchemy SQL regression suite (pytest -q test/sql): 8,327 passed,
  359 skipped
• focused APPLY/MSSQL-related regression suites: 510 passed, 3 skipped
• Black, zimports, flake8, and targeted mypy checks pass
• Sphinx reports no warnings in changed documentation
  AI tools were used in preparing this change.