refactor: change metric config to url like other module

[FoghostCn]

1. refactor: metric module use url as config class, metrics.ReporterConfig will be removed in the future
2. split metric constant to a single file

The configuration class of the metric module is a copy of the configuration class of the config package. This commit will change the configuration of the metric module to be dependent on common.URL, in order to have a consistent style with other modules.

[codecov-commenter]

Codecov Report

Merging #2396 (8b03a45) into main (0a02805) will increase coverage by 0.44%.
The diff coverage is 29.72%.

❗ Current head 8b03a45 differs from pull request most recent head 5e75c39. Consider uploading reports for the commit 5e75c39 to get more accurate results

@@            Coverage Diff             @@
##             main    #2396      +/-   ##
==========================================
+ Coverage   44.43%   44.88%   +0.44%     
==========================================
  Files         303      307       +4     
  Lines       18402    18795     +393     
==========================================
+ Hits         8177     8436     +259     
- Misses       9360     9479     +119     
- Partials      865      880      +15     

Files Changed	Coverage Δ
config/root_config.go	66.34% <0.00%> (ø)
metrics/api.go	0.00% <0.00%> (ø)
metrics/common.go	0.00% <0.00%> (ø)
metrics/prometheus/registry.go	88.88% <0.00%> (-0.31%)	⬇️
config/metric_config.go	69.76% <100.00%> (+6.91%)	⬆️

... and 8 files with indirect coverage changes

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[justxuewei]

What is the benifit of using URL to init metrics config?

I am thinking the URL is abused. It makes others confused since it is used to registry, invoker, etc. And it don't have clear semantics. They are distinguished by its protocol. Think about it, if we don't know its protocol, we can't know what it's used for.

If you still want to use a type of URL, please consider defining a new type, like MetricsAddress, or something same like that.

[FoghostCn]

What is the benifit of using URL to init metrics config?

I am thinking the URL is abused. It makes others confused since it is used to registry, invoker, etc. And it don't have clear semantics. They are distinguished by its protocol. Think about it, if we don't know its protocol, we can't know what it's used for.

If you still want to use a type of URL, please consider defining a new type, like MetricsAddress, or something same like that.

Thank you for your reply, the reason is

1. metrics.ReporterConfig is a copy of config.MetricConfig,they have duplicate fields, if we add a config field for metric module in yaml, we have to add filed both in config.MetricConfig and metrics.ReporterConfig,this is ugly.
2. common.URL is design to be a unified format for configuration information,All extension points carry configuration information by passing URL,so I think we should passing URL as configuration for metric module too.
3. other module like logger、metadata、cluster etc all use URL for configuration, other language implementations, such as Java, also follow the same approach,I think this is a default behavior.

[sonarcloud]

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[chickenlj]

Both ways can meet the requirements of passing metrics configurations for now. I think URL as the current unified design for now is acceptable.

We can revisit the design later in the following refactor plan.

[chickenlj]

LGTM.