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

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