[Issue 5430][pulsar-flink] Flink connector sink should implement consumeDataStream for 1.9.0

[fhalim]

Fixes #5430

Motivation

Should be able to write to Pulsar under Flink 1.9.0 application

Modifications

Added an implementation for StreamTableSink#consumeDataStream(DataStream) in the sink to make it compatible with Flink 1.9.0 blink.

Verifying this change

• Make sure that the change passes the CI checks.

This change added tests and can be verified as follows:

• Added unit test that verifies that a DataStreamSink is returned and is not null

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

• Dependencies (does it add or upgrade a dependency): (no)
• The public API: (no)
• The schema: (no)
• The default values of configurations: (no)
• The wire protocol: (no)
• The rest endpoints: (no)
• The admin cli options: (yes / no)
• Anything that affects deployment: (no)

Documentation

• Does this pull request introduce a new feature? (no)
• If a feature is not applicable for documentation, explain why? (Covered by Flink APIs)

[jiazhai]

@yjshen to take a look

[sijie]

As discussed in #5430, close this issue in favor of the integration in Flink community.