[CI] include-what-you-use

[marcalff]

Fixes #2052

Contributes to #2054

Changes

Please provide a brief description of the changes here.

• Add an include-what-you-use build in CI
  • Added an include-what-you-use mapping file, .iwyu.imp
  • Run include-what-you-use
  • Upload the logs as an artifact, so warnings can be investigated
  • Count the number of remaining iwyu warnings
• Cleanup for the following areas:
  • SDK, common library
  • SDK, traces library

Remaining work

The following is to be implemented later, once cleanup is completed:

• Fail the build if there are unresolved warnings

For significant contributions please make sure you have completed the following items:

• CHANGELOG.md updated for non-trivial changes
• Unit tests have been added
• Changes in public API reviewed

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 87.70%. Comparing base (497eaf4) to head (1ad587c).
Report is 68 commits behind head on main.

❗ Current head 1ad587c differs from pull request most recent head 686039d

Please upload reports for the commit 686039d to get more accurate results.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2629      +/-   ##
==========================================
+ Coverage   87.12%   87.70%   +0.58%     
==========================================
  Files         200      190      -10     
  Lines        6109     5852     -257     
==========================================
- Hits         5322     5132     -190     
+ Misses        787      720      -67     

Files	Coverage Δ
...lude/opentelemetry/sdk/common/global_log_handler.h	63.16% <ø> (-9.06%)	⬇️
...ude/opentelemetry/sdk/trace/batch_span_processor.h	100.00% <ø> (ø)
...lude/opentelemetry/sdk/trace/random_id_generator.h	100.00% <ø> (ø)
sdk/include/opentelemetry/sdk/trace/tracer.h	100.00% <ø> (ø)
...k/include/opentelemetry/sdk/trace/tracer_context.h	100.00% <ø> (ø)
sdk/src/common/base64.cc	82.40% <ø> (ø)
sdk/src/common/env_variables.cc	98.53% <ø> (ø)
sdk/src/common/platform/fork_unix.cc	100.00% <ø> (ø)
sdk/src/resource/resource.cc	96.30% <ø> (ø)
sdk/src/resource/resource_detector.cc	100.00% <ø> (ø)
... and 11 more

... and 56 files with indirect coverage changes