Please review the PR

[Jing Zhang <be...@gmail.com>]

Hi community,
Please help review the pr https://github.com/apache/calcite/pull/2606,
thanks a lot.

CALCITE-4865 is the first sub-task of CALCITE-4864. This Jira aims to
extend existing Table function in order to support Polymorphic Table
Function which is introduced as the part of ANSI SQL 2016.

The brief change logs of the PR are:
  - Update `Parser.jj` to support partition by clause and order by clause
for input table with set semantics of PTF
  - Introduce `TableCharacteristics` which contains three characteristics
of input table of table function
  - Update `SqlTableFunction` to add a method `tableCharacteristics`,  the
method returns the table characteristics for the ordinal-th argument to
this table function. Default return value is Optional.empty which means the
ordinal-th argument is not table.
  - Introduce `SqlSetSemanticsTable` which represents input table with set
semantics of Table Function, its `SqlKind` is `SET_SEMANTICS_TABLE`
  - Updates `SqlValidatorImpl` to validate only set semantic table of Table
Function could have partition by and order by clause
  - Update `SqlToRelConverter#substituteSubQuery` to parse subQuery which
represents set semantics table.

PR: https://github.com/apache/calcite/pull/2606
JIRA: https://issues.apache.org/jira/browse/CALCITE-4865
Parent JARA: https://issues.apache.org/jira/browse/CALCITE-4864

Best,
Jing Zhang