[KEPLER-MISSION] OpenConnect Runtime Optimization

OpenMessaging is a cloud native, vendor-neutral open specification for distributed messaging. By following OpenMessaging Connect API instead of a Message-Queue specific API, developers avoid repetitive work in building connector plugins for different message queues. OpenMessaging also provides a runtime specification which provides cluster management, scheduling, resource allocation and load-balancing functionality for OpenMessaging Connect. RocketMQ Runtime implements OpenMessaging Runtime.

This Topic requires you to optimize RocketMQ Connect Runtime, including
- Optimize the file connector in Connect Runtime, provide quick-start script.
- Complete the development of the Cassandra connector and optimize the runtime during the development.
- Optimize the configuration of the connect runtime clusters and the synchronization mechanism of the sites, Solve the issue that the startup speed of newly added workers is slow.
- Optimize Connect Runtime configuration information storage format to make it easier to manage.
- Optimize the connector loading mechanism, increase the configuration to determine the startup sequence of the connector and whether to start.
- Optimize the restful interface, add full start/stop and life cycle management for connector/task level
- Complete Connect Runtime docker image packaging.
- Improve the documentation.
- Other ease-of-use optimization.

OpenMessaging是云原生、厂商中立的分布式消息开放规范的集合。通过遵循OpenMessaging Connect API而不是特殊的Message Queue的API，开发人员可以避免为不同的消息队列构建connector插件。OpenMessaging还提供了一个OpenMessaging Runtime，该规范为OpenMessaging Connect提供了群集管理，调度，资源分配和负载平衡功能。 RocketMQ Runtime 实现 OpenMessaging Runtime。

本题目希望你能优化Connect Runtime，包括
- 优化Connect Runtime中的file connector，提供一键运行quick start脚本。
- 完成Cassandra connector的开发，在开发过程中优化Runtime。
- 优化Connect Runtime集群间配置、位点同步机制，解决新加入worker启动速度过慢的问题。
- 优化Connect Runtime配置信息存储格式，使其更加容易管理。
- 优化connector加载机制，增加配置决定connector的启动顺序以及是否启动。
- 优化restful接口，提升易用性，增加全量启动停止以及针对connector/task层级的生命周期管理。
- 完成Connect Runtime docker镜像打包。
- 完善文档。
- 其他易用性的优化提升。

The issue names no files, tests, or entry points; begin by locating the Connect Runtime modules and separating the listed workstreams. Choose one scoped area, then define its validation around the requested runtime, connector, REST, packaging, or documentation outcome before starting.

Written by the indexing model from the issue text.