[BUG] New engine doesn't support duplicated identifiers in the SELECT clause

[GumpacG]

What is the bug?
New engine doesn't support duplicated identifiers in the SELECT clause. This causes a legacy IT to fail when it runs on the new engine. https://github.com/opensearch-project/sql/blob/main/integ-test/src/test/java/org/opensearch/sql/legacy/QueryIT.java#:~:text=selectAllWithFieldReturnsAll

How can one reproduce the bug?
Steps to reproduce the behavior:

1. Query SELECT *, int0 from calcs
2. See error

  "error": {
    "reason": "Invalid SQL query",
    "details": "Multiple entries with same key: int0=1 and int0=1",
    "type": "IllegalArgumentException"
  },
  "status": 400
}

What is the expected behavior?
The output should be similar to Legacy where all columns are included in the result

What is your host/environment?

• OpenSearch version 2.x

[Yury-Fridlyand]

A duplicate of #785?

[GumpacG]

A duplicate of #785?

Yes, closing this issue. Thanks!