[FLINK-11009] [table] Add support for FILTER clause for non-windowed aggregation in Table API and SQL

[dianfu]

What is the purpose of the change

This pull request add the support of FILTER clause for non-windowed aggregation in Table API and SQL

Brief change log

• Update AggregateCodeGenerator to add support for FILTER clause
• Add FilterAgg operator in expression as aggregation
• Update the aggregation resolve rules in operators to resolve aggregation with filter clause
• Modify ExpressionParser for Java string-based table API

Verifying this change

This change added tests and can be verified as follows:

(example:)

• Added integration tests for built-in AGG and UDAGG respectively.
• Added unit-test for plan tests
• Added unit-test for syntactic check on both Java and Scala Table APIs
• Backward compatibility for other aggregations are covered with existing unit-test

Does this pull request potentially affect one of the following parts:

• Dependencies (does it add or upgrade a dependency): (no)
• The public API, i.e., is any changed class annotated with @Public(Evolving): (no)
• The serializers: (no)
• The runtime per-record code paths (performance sensitive): (no)
• Anything that affects deployment or recovery: JobManager (and its components), Checkpointing, Yarn/Mesos, ZooKeeper: (no)
• The S3 file system connector: (no)

Documentation

• Does this pull request introduce a new feature? (yes)
• If yes, how is the feature documented? (docs)