Introduce ValueKind to Java and add to WindowedValue

[ahmedabu98]

Adding a ValueKind representation in Java SDK
Add as a component of WindowedValue

Part of #38278
Depends on #38308 (ValueKind model) getting in first

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Summary of Changes

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This pull request adds support for tracking Change Data Capture (CDC) operation types within the Java SDK's windowed data model. By introducing a ValueKind representation and integrating it into WindowedValue, the system can now propagate information about whether a record represents an insertion, deletion, or update state through the pipeline. This change includes necessary updates to coders and builders to ensure this metadata is correctly preserved during serialization.

Highlights

• ValueKind Enum: Introduced a new ValueKind enum to represent Change Data Capture (CDC) operations such as INSERT, UPDATE_BEFORE, UPDATE_AFTER, and DELETE.
• WindowedValue Integration: Integrated ValueKind into WindowedValue and OutputBuilder to allow tracking of the operation type within windowed data elements.
• Serialization Support: Updated WindowedValueCoder and ValueKindUtil to support encoding and decoding of ValueKind in the element metadata.

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