[FLINK] Support Apache Pulsar as DataSource

[zhanglistar]

Summary

Add Gluten Flink planner/runtime support for Pulsar sources backed by Velox. Solves #12310 .
Depends on bigo-sg/velox#42 and bigo-sg/velox4j#35.

This patch:

• Adds a PulsarSourceSinkFactory that maps Flink Pulsar table/source options to Velox Pulsar connector parameters.
• Registers connector-pulsar in Gluten Flink connector config and service discovery.
• Passes the planner classloader into runtime source/sink factory discovery so planner-side factories can be loaded reliably.
• Makes blocked Velox source tasks wait instead of spinning.
• Adds unit tests for Pulsar factory discovery, connector config registration, option mapping, and wrapped Pulsar source detection.

Test Plan

• mvn -pl ut -am -Dtest=PulsarSourceSinkFactoryTest -DfailIfNoTests=false test
• Manually verified a Flink SQL Pulsar source job with parallelism 2 against local Pulsar standalone:
  • job remained RUNNING
  • two Pulsar CPP consumers were connected under a Shared subscription
  • both Flink source subtasks consumed records
  • Pulsar backlog reached 0 for the test subscription

AI Tooling Disclosure

Cowork with codex.

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[zhanglistar]

@KevinyhZou @liujiayi771 @lgbo-ustc Pls review.