[SQL] add SHOW command

[ahmedabu98]

Addresses #35637

Adds the following commands:

SHOW CATALOGS [ LIKE regex_pattern ]

+---------------------------------------+
| Catalog Name                | Type    |
+---------------------------------------+
| default                     | local   |
| my_catalog                  | local   |
| my_very_long_catalog_name   | local   |
+---------------------------------------+

SHOW DATABASES [ ( FROM | IN )? catalog_name ] [ LIKE regex_pattern ]

+-----------------------------------------+
| Databases in my_catalog                 |
+-----------------------------------------+
| default                                 |
| my_database_that_has_a_very_long_name   |
| my_db                                   |
| my_other_db                             |
+-----------------------------------------+

SHOW TABLES [ ( FROM | IN )? [ catalog_name '.' ] database_name ] [ LIKE regex_pattern ]

+--------------------------------------------+
| Tables in my_catalog.my_db        | Type   |
+--------------------------------------------+
| my_other_table                    | text   |
| my_other_table_with_a_long_name   | test   |
| my_table                          | text   |
+--------------------------------------------+

SHOW CURRENT CATALOG

my_catalog (type: iceberg)

SHOW CURRENT DATABASE

my_db

[gemini-code-assist]

Summary of Changes

Hello @ahmedabu98, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request significantly improves the introspection capabilities of the Beam SQL CLI by adding a suite of SHOW commands. These commands provide users with a clear and structured way to explore the available catalogs, databases, and tables within their SQL environment, making it easier to understand and navigate the data landscape. The changes involve updates to the SQL parser, core catalog management, and new classes to handle the execution and formatted output of these commands.

Highlights

• New SQL SHOW Commands: Introduced SHOW CATALOGS, SHOW DATABASES, SHOW TABLES, SHOW CURRENT CATALOG, and SHOW CURRENT DATABASE commands to the Beam SQL CLI.
• Catalog and Database Introspection: Added functionality to list available catalogs, databases within the current catalog, and tables within the current database, enhancing visibility into the SQL environment.
• Parser and Schema Integration: Integrated the new SHOW commands into the SQL parser and extended the Catalog, CatalogSchema, and BeamCalciteSchema interfaces and implementations to support retrieving and displaying this metadata.

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[github-actions]

Checks are failing. Will not request review until checks are succeeding. If you'd like to override that behavior, comment assign set of reviewers

[ahmedabu98]

Failing tests are unrelated

[ahmedabu98]

assign set of reviewers

[github-actions]

Assigning reviewers:

R: @m-trieu for label java.

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[github-actions]

Reminder, please take a look at this pr: @m-trieu

[github-actions]

Assigning new set of reviewers because Pr has gone too long without review. If you would like to opt out of this review, comment assign to next reviewer:

R: @kennknowles for label java.

Available commands:

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[github-actions]

Reminder, please take a look at this pr: @kennknowles

[derrickaw]

waiting on author

[ahmedabu98]

@kennknowles thx for the comments. This is ready for another review

cc @talatuyarer