[FLINK-38791][table] Add support for ALTER MATERIALIZED TABLE MODIFY

[snuyanzin]

What is the purpose of the change

The next part of FLIP-550 which adds support for ALTER MATERIALIZED TABLE MODIFY in way like

ALTER MATERIALIZED TABLE myMaterializedTable MODIFY c1 AS current_timestamp COMMENT 'new_column docs';

and

ALTER MATERIALIZED TABLE myMaterializedTable MODIFY (
     ts AS current_timestamp FIRST,
     col_meta INT METADATA FROM 'mk1' VIRTUAL AFTER col_b,
     PRIMARY KEY (id) NOT ENFORCED,
     WATERMARK FOR ts AS ts - INTERVAL '3' SECOND
);

Brief change log

parser and converters

Verifying this change

parser and converter's test added

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? (no, there will be a separate PR for docs)
• If yes, how is the feature documented? (not applicable)

[flinkbot]

CI report:

• 8a0ef6b Azure: SUCCESS

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[davidradl]

nit: I am curious why do we have a mix of LPAREN and ( . I assume we should use LPAREN for all left brackets so it uses the grammar constant.

[snuyanzin]

<LPAREN> means there will be a token parsed if it faces ( in sql
( is just a part of syntax which has nothing to do with <LPAREN>

[snuyanzin]

it just says that if it meets something matching
inside (...)* then it should expect it arbitrary amount of times

[twalthr]

Thank you @snuyanzin. I just had minor comments. LGTM overall.

[twalthr]

Is this new logic or was this previous behavior?

[snuyanzin]

added a comment referencing code for CREATE [MATERIALIZED ]TABLE path with similar logic

[twalthr]

LGTM. Thanks @snuyanzin

[snuyanzin]

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