Add internal logging to HTTP libraries

[cijothomas]

Fixes #2446

It's now easy to debug, especially since tracing::fmt can also show the thread from which the calls are made!

2024-12-18T20:09:59.890413Z DEBUG tokio-runtime-worker opentelemetry_sdk:  name="PeriodicReaderWorker.InvokeExporter" Calling exporter's export method with collected metrics. count=1
2024-12-18T20:09:59.890457Z DEBUG tokio-runtime-worker opentelemetry-otlp:  name="HttpMetricsClient.CallingExport"
2024-12-18T20:09:59.890462Z DEBUG tokio-runtime-worker opentelemetry-http:  name="ReqwestClient.Send"

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 6 lines in your changes missing coverage. Please review.

Project coverage is 76.1%. Comparing base (938893c) to head (7cd3c78).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
opentelemetry-http/src/lib.rs	0.0%	3 Missing ⚠️
opentelemetry-otlp/src/exporter/http/logs.rs	0.0%	1 Missing ⚠️
opentelemetry-otlp/src/exporter/http/metrics.rs	0.0%	1 Missing ⚠️
opentelemetry-otlp/src/exporter/http/trace.rs	0.0%	1 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##            main   #2452     +/-   ##
=======================================
- Coverage   76.1%   76.1%   -0.1%     
=======================================
  Files        122     122             
  Lines      22056   22062      +6     
=======================================
  Hits       16790   16790             
- Misses      5266    5272      +6     

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