[Shims, W3C.Tests] Nullable

[ysolomchenko]

Towards #3958

Changes

• Shims.OpenTracing mark as nullable
• Instumentation.W3cTraceContext.Tests mark as nullable

Merge requirement checklist

• CONTRIBUTING guidelines followed (license requirements, nullable enabled, static analysis, etc.)
• Unit tests added/updated
• Appropriate CHANGELOG.md files updated for non-trivial changes
• Changes in public API reviewed (if applicable)

[codecov]

Codecov Report

Attention: Patch coverage is 82.35294% with 6 lines in your changes missing coverage. Please review.

Project coverage is 86.22%. Comparing base (6250307) to head (c230635).
Report is 316 commits behind head on main.

Files with missing lines	Patch %	Lines
src/OpenTelemetry.Shims.OpenTracing/SpanShim.cs	69.23%	4 Missing ⚠️
...OpenTelemetry.Shims.OpenTracing/SpanBuilderShim.cs	94.11%	1 Missing ⚠️
src/OpenTelemetry.Shims.OpenTracing/TracerShim.cs	50.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #5797      +/-   ##
==========================================
+ Coverage   83.38%   86.22%   +2.84%     
==========================================
  Files         297      257      -40     
  Lines       12531    11169    -1362     
==========================================
- Hits        10449     9631     -818     
+ Misses       2082     1538     -544     

Flag	Coverage Δ
unittests	?
unittests-Project-Experimental	85.95% <82.35%> (?)
unittests-Project-Stable	86.22% <82.35%> (?)
unittests-UnstableCoreLibraries-Experimental	85.71% <82.35%> (?)

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
...penTelemetry.Shims.OpenTracing/ScopeManagerShim.cs	96.77% <100.00%> (ø)
...OpenTelemetry.Shims.OpenTracing/SpanBuilderShim.cs	90.58% <94.11%> (-0.11%)	⬇️
src/OpenTelemetry.Shims.OpenTracing/TracerShim.cs	91.66% <50.00%> (ø)
src/OpenTelemetry.Shims.OpenTracing/SpanShim.cs	80.20% <69.23%> (-1.32%)	⬇️

... and 219 files with indirect coverage changes

[Kielek]

LGTM.

@CodeBlanch, could you please also check and merge?

[github-actions]

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[TimothyMothra]

🎉

[TimothyMothra]

LGTM! :)