MSQ window functions: Fix partition boundary issues for arrays

[Akshat-Jain]

Description

Currently, queries like the following give incorrect results:

select countryName, cityName, channel, 
row_number() over (partition by array[1,2,length(cityName)] order by countryName) as c
from wikipedia
where countryName in ('Austria', 'Republic of Korea')
group by countryName, cityName, channel

This is because while calculating the partitioning boundaries, we use Objects.equals() to check the value for partition column. But it returns false when trying to compare [1,2,null] against [1,2,null] because of the presence of null value.

This PR changes the comparison logic to use NullableTypeStrategy for the column type.

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This PR has:

• been self-reviewed.
• 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.

[sreemanamala]

lgtm. added a couple of nit comments. should be fine either way.

[LakshSingla]

MSQ changes LGTM