feat(simulator): add SQL execution support with MySQL and PostgreSQL

[chhil]

Implements optional pre/post-SQL execution in test cases with configurable error handling.

Summary

• Add preSQL and postSQL fields to TestCase with getters/setters
• Add continueOnSqlError option to control SQL failure behavior (default: continue)
• Add SQLFailureException for strict SQL error handling
• Add executeSQL() method to TestRunner using Hibernate Work interface
• Parse pre-sql/post-sql XML elements in test suite configuration
• Support continue-on-sql-error attribute on test elements
• Execute SQL before request (preSQL) and after response (postSQL)
• Support semicolon-separated multiple SQL statements
• Log SELECT results and affected row counts
• Add MySQL test support via Testcontainers

Documentation

• Complete SQL execution support documentation with examples
• Execution order: init, pre-sql, request/response, post, post-sql
• When to use SQL execution (balance setup, limits, state reset)
• Database configuration and db.properties examples
• init script scoping with suite-level and test-level differences
• Database dependencies (PostgreSQL, MySQL, H2) for Gradle
• Supported databases with behavioral differences

Tests

• 36 tests covering SQL functionality, backward compatibility, and error handling
• Tests run against both PostgreSQL (default) and MySQL via test.clientsim_db_driver
• Driver-aware DDL syntax ensures cross-database compatibility

Behavior

• By default, SQL errors are logged but don't fail the test (backward compatible)
• Set continue-on-sql-error="no" to fail test on SQL error
• SQL feature is purely opt-in - existing configs work unchanged

Assisted-by

Qwen36

[ar-agt]

Thanks for this contribution. SQL setup/cleanup around Client Simulator tests is a very useful addition and will come in handy for stateful simulator scenarios, especially balance setup, limits, and deterministic cleanup between cases.

I think this needs a small rework before merge:

1. continue-on-sql-error="no" can still report the test as OK in some paths.

   • For pre-sql, runSuite sets FAILURE on SQLFailureException, but when continue="yes" is set it falls through and still sends the request; assertResponse can then overwrite the result to OK.
   • For fire-and-forget tests, a strict post-sql failure sets FAILURE, but the path later unconditionally calls tc.setResultCode(TestCase.OK).

2. The tests should exercise the new TestRunner path directly. Right now several SQL tests open DB and execute JDBC work directly, so they do not prove that executeSQL, XML parsing of pre-sql/post-sql, or the runSuite ordering/error handling work correctly.

3. Please fix the Javadoc markup errors introduced by the new docs (unexpected end tag: </p> in TestRunner, TestCase, and SQLFailureException). The current build does not fail on those errors, but we should not add known broken Javadocs.

4. Please keep the diff tighter if possible. The feature is good, but the broad reformatting/Javadoc churn around existing code makes review harder than it needs to be.

Verification I ran:

• ./gradlew :modules:client-simulator:test passed with PostgreSQL.
• ./gradlew :modules:client-simulator:test -Dtest.clientsim_db_driver=mysql passed.
• A local no-commit merge with current origin/main, then ./gradlew :modules:client-simulator:test :modules:client-simulator:build, passed, with the Javadoc errors noted above.