[Code Health] include-what-you-use cleanup, part 4

[marcalff]

Contributes to #2054

Changes

Please provide a brief description of the changes here.

• completed cleanup of sdk/include
• completed cleanup of sdk/src
• major cleanup of sdk/test, with only 8 issues remaining
• total number of warnings decreased from 91 in branch main, to 29 in this PR.

The remaining sdk warnings need more analysis, and will be fixed in a different PR.

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 87.79%. Comparing base (497eaf4) to head (293e457).
Report is 130 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3040      +/-   ##
==========================================
+ Coverage   87.12%   87.79%   +0.68%     
==========================================
  Files         200      195       -5     
  Lines        6109     5953     -156     
==========================================
- Hits         5322     5226      -96     
+ Misses        787      727      -60     

Files with missing lines	Coverage Δ
...entelemetry/exporters/memory/in_memory_span_data.h	100.00% <ø> (ø)
...lemetry/exporters/memory/in_memory_span_exporter.h	89.48% <ø> (-1.43%)	⬇️
...include/opentelemetry/ext/http/common/url_parser.h	93.94% <ø> (+1.94%)	⬆️
...include/opentelemetry/sdk/common/attribute_utils.h	89.84% <ø> (-1.07%)	⬇️
...clude/opentelemetry/sdk/common/attributemap_hash.h	90.00% <ø> (+6.13%)	⬆️
...include/opentelemetry/sdk/common/circular_buffer.h	100.00% <ø> (ø)
...e/opentelemetry/sdk/common/circular_buffer_range.h	100.00% <ø> (ø)
...nclude/opentelemetry/sdk/metrics/observer_result.h	100.00% <ø> (+7.70%)	⬆️
...entelemetry/sdk/metrics/state/attributes_hashmap.h	92.19% <ø> (-0.23%)	⬇️
...telemetry/sdk/metrics/state/multi_metric_storage.h	81.82% <ø> (-1.51%)	⬇️
... and 9 more

... and 109 files with indirect coverage changes

[marcalff]

Massive cleanup in sdk and misc places, now ready for review.

[esigo]

LGTM
thanks for the PR :)