feat: extend INSERT/VALUES syntax for multiple rows

[spena]

Description

Extends the INSERT ... VALUES syntax to accept multiple rows. For instance:

INSERT INTO foo VALUES (10), (11), (12);

The topic foo will contain three 3 rows (10, 11 and 12)

The above statement is equivalent to:

INSERT INTO foo VALUES (10);
INSERT INTO foo VALUES (11);
INSERT INTO foo VALUES (12);

Testing done

Modified unit tests Verified manually running the CLI

ksql> insert into t1(id) values (1),(2);
ksql> select * from t1 emit changes;
+-------------------------------------------+-------------------------------------------+-------------------------------------------+
|ROWTIME                                    |ROWKEY                                     |ID                                         |
+-------------------------------------------+-------------------------------------------+-------------------------------------------+
|1578687132771                              |null                                       |1                                          |
|1578687132796                              |null                                       |2                                          |

Reviewer checklist

• [ ] Ensure docs are updated if necessary. (eg. if a user visible feature is being added or changed).
• [ ] Ensure relevant issues are linked (description should include text like "Fixes #")

[JimGalasyn]

@spena, now that we have a 5.4.0-post branch, do you want to re-target this PR to the 5.4.x branch?

[JimGalasyn]

@agavra, now that we have a 5.4.0-post branch, do you want to re-target this PR to the 5.4.x branch?

[agavra]

@JimGalasyn - I'm not sure this feature makes sense to backport to 5.4 as it's exclusively new functionality. Is there any reason we should do that?

[JimGalasyn]

Ah you're right, it's a new feature, so it won't be going out with 5.4.1. Never mind!

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