Append 2 AS operators in SqlNode representation for LATERAL VIEWS

[aastha25]

For RelNode -> SqlNode translations for SQLs with LATERAL VIEW UNNEST(..), Coral only appends one (inner) AS operator. The output SqlNode generated looks like - SELECT t0.ccol .... LATERAL VIEW UNNEST(col) AS t0 (ccol)...

However, the same underlying code in Calcite appends 2 AS operators in the following fashion - SELECT t00.ccol .... LATERAL VIEW UNNEST(col) AS t0 (ccol) AS t00....

Why does Coral deviate and is it possible to follow the original Calcite syntax in Coral?

[aastha25]

Also, when an input hive SQL with LATERAL VIEW UNNEST(..) is converted to CoralSqlNode, it is represented using one AS operator. We should also represent this CoralSqlNode using 2 AS operators for consistency and symmetry.