coalesce on unnest row mismatch fix

[somu-imply]

A query of form

select coalesce(c,s_int) as col from test_unnest_test_sql_array, unnest(json_value(a_nested, '$[1]' returning bigint array)) as u(c) 

due to a type mismatch while working on nested arrays with the trace

Caused by: java.lang.IllegalArgumentException: Type mismatch:
rel rowtype: RecordType(BIGINT NOT NULL ARRAY $f0, BIGINT NOT NULL $f00) NOT NULL
equiv rowtype: RecordType(BIGINT NOT NULL ARRAY $f11, BIGINT col) NOT NULL
Difference:
$f00: BIGINT NOT NULL -> BIGINT

        at org.apache.calcite.plan.volcano.VolcanoPlanner.register(VolcanoPlanner.java:592) ~[calcite-core-1.35.0.jar:1.35.0]
        at org.apache.calcite.plan.volcano.VolcanoPlanner.ensureRegistered(VolcanoPlanner.java:613) ~[calcite-core-1.35.0.jar:1.35.0]
        at org.apache.calcite.plan.volcano.VolcanoRuleCall.transformTo(VolcanoRuleCall.java:144) ~[calcite-core-1.35.0.jar:1.35.0]
        at org.apache.calcite.plan.RelOptRuleCall.transformTo(RelOptRuleCall.java:273) ~[calcite-core-1.35.0.jar:1.35.0]
        at org.apache.calcite.plan.RelOptRuleCall.transformTo(RelOptRuleCall.java:288) ~[calcite-core-1.35.0.jar:1.35.0]
        at org.apache.druid.sql.calcite.rule.DruidCorrelateUnnestRule.onMatch(DruidCorrelateUnnestRule.java:178) ~[druid-sql-28.0.0-SNAPSHOT.jar:28.0.0-SNAPSHOT]
        at org.apache.calcite.plan.volcano.VolcanoRuleCall.onMatch(VolcanoRuleCall.java:223) ~[calcite-core-1.35.0.jar:1.35.0]
        at org.apache.calcite.plan.volcano.IterativeRuleDriver.drive(IterativeRuleDriver.java:59) ~[calcite-core-1.35.0.jar:1.35.0]
        at org.apache.calcite.plan.volcano.VolcanoPlanner.findBestExp(VolcanoPlanner.java:523) ~[calcite-core-1.35.0.jar:1.35.0]
        at org.apache.calcite.tools.Programs$RuleSetProgram.run(Programs.java:317) ~[calcite-core-1.35.0.jar:1.35.0]
        at org.apache.calcite.tools.Programs$SequenceProgram.run(Programs.java:337) ~[calcite-core-1.35.0.jar:1.35.0]
        at org.apache.druid.sql.calcite.planner.CalcitePlanner.transform(CalcitePlanner.java:452) ~[druid-sql-28.0.0-SNAPSHOT.jar:28.0.0-SNAPSHOT]
        at org.apache.druid.sql.calcite.planner.QueryHandler.planWithDruidConvention(QueryHandler.java:590) ~[druid-sql-28.0.0-SNAPSHOT.jar:28.0.0-SNAPSHOT]
        at org.apache.druid.sql.calcite.planner.QueryHandler$SelectHandler.planForDruid(QueryHandler.java:738) ~[druid-sql-28.0.0-SNAPSHOT.jar:28.0.0-SNAPSHOT]
        at org.apache.druid.sql.calcite.planner.QueryHandler.plan(QueryHandler.java:220) ~[druid-sql-28.0.0-SNAPSHOT.jar:28.0.0-SNAPSHOT]
        ... 83 more

After this change, the query executes correctly.

This is a work in progress towards handling it. Although this fixes it, am looking into casts in the NestedDataExpressions if we can handle casts correctly there

This PR has:

• been self-reviewed.
  • using the concurrency checklist (Remove this item if the PR doesn't have any relation to concurrency.)
• added documentation for new or modified features or behaviors.
• a release note entry in the PR description.
• added Javadocs for most classes and all non-trivial methods. Linked related entities via Javadoc links.
• added or updated version, license, or notice information in licenses.yaml
• added comments explaining the "why" and the intent of the code wherever would not be obvious for an unfamiliar reader.
• added unit tests or modified existing tests to cover new code paths, ensuring the threshold for code coverage is met.
• added integration tests.
• been tested in a test Druid cluster.