[General][Java SDK (Component)] Metrics module refactoring plan

[walklown]

Separate the code for indicator monitoring

Goal

• Make Dubbo core no longer dependent on dubbo-metrics module.

Schedule

• Issue
• Pull request

Allow modules to extend Dubbo application configuration

Goal

• Move MetricsConfig and PromethusConfig back to the dubbo-metrics module.
• Allow custom configuration when extending the new dubbo-metrics-export module.
• (Maybe) Remove AbstractConfig.

Schedule

• Issue

Refector Metric export

Goal

• Implement dubbo-metrics with micrometer. The dubbo-metrics module will be more standardized and general.
  

Schedule

• Issue