Added BatchSpanProcessor metrics on drop and export span

[mamunto]

Added BatchSpanProcessor metrics on drop and export span

[mamunto]

I'm following Java SDK implementation from here

[bryce-b]

Looks good, I'll approve it after you add the // TODO: Record a gauge for referenced spans. if you want to do that.

[mamunto]

Clean up here cc: @bryce-b

[nachoBonafonte]

Sorry for being late, but I have some questions about the new protocol functions and how they match in the API/SDK

[mamunto]

Sorry for being late, but I have some questions about the new protocol functions and how they match in the API/SDK

I followed exactly how it defined in the Java SDK. We can discuss more today's session

[mamunto]

Here is the Java SDK:

https://github.com/open-telemetry/opentelemetry-java/blob/main/sdk/trace/src/main/java/io/opentelemetry/sdk/trace/export/BatchSpanProcessor.java

[nachoBonafonte]

LGTM, thanks for addressing all the feedback. I will let @bryce-b merge if he considers it ready also.

[codecov]

Codecov Report

Attention: Patch coverage is 78.88889% with 19 lines in your changes missing coverage. Please review.

Project coverage is 67.54%. Comparing base (7bad8ae) to head (675694f).
Report is 42 commits behind head on main.

Files with missing lines	Patch %	Lines
...ySdk/Trace/SpanProcessors/BatchSpanProcessor.swift	78.88%	19 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #635      +/-   ##
==========================================
- Coverage   67.89%   67.54%   -0.35%     
==========================================
  Files         344      352       +8     
  Lines       15169    15873     +704     
==========================================
+ Hits        10299    10722     +423     
- Misses       4870     5151     +281     

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

---

🚨 Try these New Features:

• Flaky Tests Detection - Detect and resolve failed and flaky tests