Recognize CROSS APPLY and OUTER APPLY

[radixun]

Fixes #300.

Recognize SQL Server's CROSS APPLY and OUTER APPLY as compound keywords. Previously, keyword_case='upper' left apply unchanged. Parsing also grouped apply with the next table-valued function and separated the function from its alias.

Add tests for both operators, case changes, whitespace, table-source boundaries, identifiers and quoted text. Keep standalone apply as an identifier.

• Tests: 547 passed, 2 xfailed, 1 xpassed on Linux with Python 3.14.4. The xfail and xpass results also occur on the base.
• Ruff: ruff check sqlparse/ tests/test_apply.py.
• Regression tests cover the change.
• Add a changelog entry.