Implement PEP 249-compliant transaction control with extensions formanual commit/rollback operations. This enables atomic multi-tableoperations with REPEATABLE_READ isolation semantics.Core API additions:- connection.autocommit property for enabling/disabling auto-commit mode- connection.commit() to commit active transactions- connection.rollback() to rollback active transactions- connection.get_transaction_isolation() returns current isolation level- connection.set_transaction_isolation() validates isolation level- TransactionError exception for transaction-specific failuresImplementation details:- Added autocommit state caching in Session with optional server query- Added TRANSACTION_ISOLATION_LEVEL_REPEATABLE_READ constant- All transaction operations include proper error handling and telemetry- Supports fetch_autocommit_from_server connection parameterTesting:- Unit tests covering all transaction methods and error scenarios- e2e integration tests validating transaction behavior including  multi-table atomicity, sequential transactions, and isolation semanticsDocumentation:- Comprehensive TRANSACTIONS.md guide with examples and best practices- Updated README.md with basic usage and reference to detailed docsRequires MST-enabled Databricks SQL warehouse and Delta tables with'delta.feature.catalogOwned-preview' table property.