Sentinel feature: add metric exporter interface

Describe what this PR does / why we need it

https://github.com/alibaba/Sentinel/issues/3314

Does this pull request fix one issue?

Describe how you did it

Describe how to verify it

Special notes for reviews

Jun 09 '24 12:06 Daydreamer-ia

We may need to discuss whether we should support having multiple exporters active at the same time. I'm not sure about your perspective on this.

Aug 23 '24 03:08 LearningGp

We may need to discuss whether we should support having multiple exporters active at the same time. I'm not sure about your perspective on this.

I keep one leave is order to sync the old logic, to be honest, i agree with you that support multiple exporters here. Do i keep more exporters active this pr?

Sep 25 '24 14:09 Daydreamer-ia

We may need to discuss whether we should support having multiple exporters active at the same time. I'm not sure about your perspective on this.

I keep one leave is order to sync the old logic, to be honest, i agree with you that support multiple exporters here. Do i keep more exporters active this pr?

For this PR, let's keep the single export implementation as is.

Sep 17 '25 12:09 LearningGp