Core, Data: Validate equality delete field IDs

[u70b3]

Summary

This PR brings stricter equality delete field ID validation into the Java SDK, aligned with the behavior added in iceberg-rust#2723.

The validation now rejects:

• Null or empty equality field ID lists
• Duplicate equality field IDs
• Equality field IDs that do not exist in the equality delete row schema

Changes

• Centralized validation in DeleteSchemaUtil.validateEqualityFieldIds.
• Applied validation to direct Avro, Parquet, ORC equality delete writer builders.
• Applied validation to the registry-based writer path through FileWriterBuilderImpl.
• Updated data writer/appender factories to validate against the equality delete row schema, not the data schema.
• Added regression coverage for projected schemas, null data schema equality-delete-only construction, empty IDs, duplicate IDs, and missing IDs.

Testing

• ./gradlew :iceberg-core:test --tests org.apache.iceberg.avro.TestAvroDeleteWriters --tests org.apache.iceberg.formats.TestFormatModelRegistry :iceberg-data:test --tests org.apache.iceberg.data.TestGenericFileWriterFactory --tests org.apache.iceberg.TestGenericAppenderFactory :iceberg-parquet:test --tests org.apache.iceberg.parquet.TestParquetDeleteWriters :iceberg-orc:test --tests org.apache.iceberg.orc.TestOrcDeleteWriters :iceberg-core:spotlessCheck :iceberg-data:spotlessCheck :iceberg-parquet:spotlessCheck :iceberg-orc:spotlessCheck

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AI Disclosure

• Model: GPT-5
• Platform/Tool: Codex
• Human Oversight: partially reviewed
• Prompt Summary: Fix equality delete field ID validation findings, compare with the original PR, and update the existing PR branch as a single commit.