Check for Aggregation inside a window clause when syntax used as - WINDOW W AS DEF

[sreemanamala]

Description

Currently calcite does not support a window query where aggregation is present on the nodes inside window clause if the window is provided in the select list. So this commit checks for such cases and provide an actionable error msg to use a different syntax.
example:

SELECT
row_number() over w as c
FROM table
WINDOW w as (partition by aggr(col1) order by col2)

would not work. Where as

SELECT
row_number() over (partition by aggr(col1) order by col2) as c
FROM table

works fine.

This check is to be removed once CALCITE-6500 is fixed

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Key changed/added classes in this PR

• DruidSqlValidator

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This PR has:

• been self-reviewed.
  • using the concurrency checklist (Remove this item if the PR doesn't have any relation to concurrency.)
• added documentation for new or modified features or behaviors.
• a release note entry in the PR description.
• added Javadocs for most classes and all non-trivial methods. Linked related entities via Javadoc links.
• added or updated version, license, or notice information in licenses.yaml
• added comments explaining the "why" and the intent of the code wherever would not be obvious for an unfamiliar reader.
• added unit tests or modified existing tests to cover new code paths, ensuring the threshold for code coverage is met.
• added integration tests.
• been tested in a test Druid cluster.

[kgyrtkirk]

looks good!
just some minor changes + green run is needed