[FLINK-37827][table] Add support for SHOW CREATE MATERIALIZED TABLE

[snuyanzin]

What is the purpose of the change

The PR to support SHOW CREATE MATERIALIZED TABLE,
looks like this is a missed thing from FLINK-35187

Brief change log

parser, ShowCreateUtil ,tests

Verifying this change

Mostly ShowCreateUtilTest

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, Kubernetes/Yarn, 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? ( not documented (seems the generic issue for Materialized table which should be addressed under FLINK-35688))

[flinkbot]

CI report:

• 2434327 Azure: SUCCESS

Bot commands

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[snuyanzin]

@flinkbot run azure

[twalthr]

Thank you for leaving the code base in a better shape. I had just one last comment and potentially a followup task.

[twalthr]

Would the SQL parser allow parsing INTERVAL '5' DAY. Doesn't it need to be plural. Also why is the interval a string, this looks like a bug to me. Maybe we should change it before it is too late.

[twalthr]

Ok it seems the SQL parser allows parsing INTERVAL '5' DAY