[feat][io] Add Debezium MariaDB source connector

[david-streamlio]

Motivation

Debezium ships a MariaDB source connector (io.debezium:debezium-connector-mariadb, present in the debezium-bom at our pinned version), but this repository does not wrap it. We currently wrap 5 of Debezium's 12 source connectors: MySQL, PostgreSQL, MongoDB, Oracle, and SQL Server.

MariaDB is the highest-value gap:

• Debezium split the MariaDB connector out of the MySQL connector, and both now build on the shared debezium-connector-binlog base. Our existing debezium/mysql module is therefore close to a drop-in template for the connector, the config plumbing, and the integration test.
• We already ship a MariaDB JDBC sink (jdbc/mariadb, integration test added in [improve][test] Add MariaDB JDBC sink integration test #59), so a MariaDB source completes the story for that database.

Proposal

Add a debezium/mariadb module (pulsar-io-debezium-mariadb) following the structure of debezium/mysql:

• DebeziumMariaDbSource extending DebeziumSource, asserting Debezium's connector.class/task.class for the MariaDB connector
• include("debezium:pulsar-io-debezium-mariadb") in settings.gradle.kts
• debezium-connector-mariadb = { module = "io.debezium:debezium-connector-mariadb" } in the version catalog
• NAR packaging + distribution wiring, mirroring the MySQL module
• A Testcontainers integration test cloned from DebeziumMysqlSourceTest

Notes

• Use the GenericContainer pattern rather than a specialized Testcontainers module: debezium-bom pins Testcontainers core to 2.x while the specialized modules still target 1.21.x and reference shaded classes removed in 2.x (see the discussion in [improve][test] Add Debezium Oracle source integration test #62).
• MariaDB is a single-partition connector, so it should not hit the task.id gap described in [Bug] Debezium SQL Server source fails to start: multi-partition connector never receives task.id #61.

Identified by a scan of the Debezium connector catalog against our connector inventory.