[Beam SQL] Support DATABASE concept in Beam SQL, with implementation for Iceberg

[ahmedabu98]

Addresses #35637

These changes allow the following:

• CREATE DATABASE ( IF NOT EXISTS )? database_name
• USE DATABASE database_name
• DROP DATABASE [ IF EXISTS ] database_name [ RESTRICT | CASCADE ]
  • RESTRICT (default) will throw an error if the database contains a table. CASCADE will drop all tables within the database before dropping the database.

For Iceberg catalogs, CREATE and DROP will create/drop real external tables in the appropriate data platform.

These implementations will help bring Beam closer to alignment with existing Flink and Spark syntax

[ahmedabu98]

cc @talatuyarer

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[ahmedabu98]

R: @tarun-google

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[tarun-google]

LGTM !! Great work fixing gap in Iceberg Beam SQL

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 56.54%. Comparing base (ce77091) to head (17993a3).
Report is 13 commits behind head on master.

Additional details and impacted files

@@ Coverage Diff @@## master #35641 +/- ##
=========================================
Coverage 56.54% 56.54% Complexity 3382 3382 =========================================
Files 1205 1205 Lines 183856 183856 Branches 3477 3477 =========================================
Hits 103961 103961 Misses 76577 76577 Partials 3318 3318 

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