Base window extension for named windows

[jwgmeligmeyling]

From Slack

Description

The WindowBuilder seems to miss a setter to set the identifier from the base window, but nesting windows seems allowed from the grammar: https://github.com/Blazebit/blaze-persistence/blob/master/core/parser/src/main/antlr4/com/blazebit/persistence/parser/JPQLNextParser.g4#L325-L330

The suggested fix is to add a method WindowBuilder#window(windowName, baseWindowName) through which a window can be created that extends an existing window.

Expected behavior

Actual behavior

Steps to reproduce

Environment

Version:
JPA-Provider:
DBMS:
Application Server:

[beikov]

We can introduce that method, but I think nesting windows will complicate things.