feat: adding default set of counters for retry wrappers

[eledhwen]

Additions:

• adding default set of counters for retry wrappers (RetryStep and RetrySink)
• MeterRegistryKey can now fill-in counters with arbitrary ids

Additional metrics for steps are the following:

• pipeline.step.retry.run_count (count) : how many times the wrapper was executed
• pipeline.step.retry.run_success (count) : how many times the wrapper succeeded
• pipeline.step.retry.run_failure (count) : how many times the wrapper failed (retry exhausted)
• pipeline.step.retry.retry_count (count) : how many times a retry was attempted
• pipeline.step.retry.retry_success (count) : how many times a retry attempt succeeded
• pipeline.step.retry.retry_failure (count) : how many times a retry attempt failed

Additional metrics for sinks are the following:

• pipeline.sink.retry.run_count (count) : how many times the wrapper was executed
• pipeline.sink.retry.run_success (count) : how many times the wrapper succeeded
• pipeline.sink.retry.run_failure (count) : how many times the wrapper failed (retry exhausted)
• pipeline.sink.retry.retry_count (count) : how many times a retry was attempted
• pipeline.sink.retry.retry_success (count) : how many times a retry attempt succeeded
• pipeline.sink.retry.retry_failure (count) : how many times a retry attempt failed

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 84.00000% with 4 lines in your changes missing coverage. Please review.

Project coverage is 82.29%. Comparing base (e12d48c) to head (0093901).

Files with missing lines	Patch %	Lines
...ine/resilience4j/sink/wrapper/retry/RetrySink.java	77.77%	2 Missing ⚠️
...ine/resilience4j/step/wrapper/retry/RetryStep.java	84.61%	2 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##             master     #145      +/-   ##
============================================
- Coverage     82.31%   82.29%   -0.03%     
- Complexity      789      792       +3     
============================================
  Files           147      147              
  Lines          2098     2118      +20     
  Branches        120      120              
============================================
+ Hits           1727     1743      +16     
- Misses          291      295       +4     
  Partials         80       80              

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

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.