Multi-writer unique key enforcement for OCC/NBCC

When multiple writers try to insert records of the same record key that does not exsit in the table, both writers can succeed leading to duplicates in the table.  In reality, this might not happen in common use cases (e.g., streaming CDC logs to table through Kafka).  Still, if we'd like to strictly guarantee key uniqueness for concurrent inserts, we may need the Hudi index to be aware of multiple writers (right now the index only reads committed data), so that we can efficiently identify the same record key across multiple writers.

## JIRA info

- Link: https://issues.apache.org/jira/browse/HUDI-8142
- Type: Task
- Epic: https://issues.apache.org/jira/browse/HUDI-6640
- Fix version(s):
- 1.1.0

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## Comments

23/Sep/24 18:55;yihua;Deferring this to Hudi 1.1.0 since the multi-writer unique key enforcement for inserts require fundamental redesign on concurrency control and indexing.;;;