Support defining windowing behavior in the WINDOW clause

PostgreSQL and SparkSQL support defining the windowing behavior in the WINDOW clause and then referenced in OVER.
This is very useful if the same windowing behavior is wanted for several functions.

For example:

````
SELECT sum(salary) OVER w, avg(salary) OVER w
FROM empsalary
WINDOW w AS (PARTITION BY depname ORDER BY salary DESC);

````

https://www.postgresql.org/docs/15/tutorial-window.html

https://www.postgresql.org/docs/15/sql-expressions.html#SYNTAX-WINDOW-FUNCTIONS

首先追蹤 parser 如何處理 WINDOW 和 OVER 語法，並使用 issue 中的 PostgreSQL 範例作為語法參考。定義具名視窗定義和參照所需的解析行為，然後新增測試涵蓋範圍，證明兩個函式都可以重複使用 w，且範例能夠被解析。

由索引模型根據 Issue 內容生成。