Create generic statsReporter in metrics package

[Leo6Leo]

Proposed Changes

• Create the generic StatsReporter in the metrics package
• Merge all the existing statsReporter to use this generic statsreporter
• Modify the corresponding unit tests

Pre-review Checklist

• At least 80% unit test coverage
• E2E tests for any new behavior
• Docs PR for any user-facing impact
• Spec PR for any new API feature
• Conformance test for any change to the spec

Release Note

Docs

[knative-prow]

Skipping CI for Draft Pull Request.
If you want CI signal for your change, please convert it to an actual PR.
You can still manually trigger a test run with /test all

[Cali0707]

@Leo6Leo can you rebase?

[knative-prow]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: Leo6Leo

The full list of commands accepted by this bot can be found here.

The pull request process is described here

Needs approval from an approver in each of these files:

• OWNERS [Leo6Leo]

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment

[Leo6Leo]

/cc @creydr

I re-write the statsReport to make it more generic and moved it to the metrics package by following the suggestions you left here.

Please let me know if this is on the right track, then I will proceed changing the statsReporter for channel, broker ingress... to use the new generic statsReporter.

[creydr]

@Leo6Leo can you check on the failing tests?

[codecov]

Codecov Report

Attention: Patch coverage is 86.66667% with 2 lines in your changes missing coverage. Please review.

Project coverage is 67.74%. Comparing base (71d5d5f) to head (e1aa68a).
Report is 57 commits behind head on main.

Files with missing lines	Patch %	Lines
pkg/metrics/stats_reporter.go	86.66%	1 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #8084      +/-   ##
==========================================
+ Coverage   67.71%   67.74%   +0.03%     
==========================================
  Files         370      371       +1     
  Lines       17946    17965      +19     
==========================================
+ Hits        12152    12171      +19     
  Misses       5020     5020              
  Partials      774      774              

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[github-actions]

This Pull Request is stale because it has been open for 90 days with
no activity. It will automatically close after 30 more days of
inactivity. Reopen with /reopen. Mark as fresh by adding the
comment /remove-lifecycle stale.