[wcf] Streamline the exposed public interface (breaking change)

[repl-chris]

Changes

This moves the TelemetryClientMessageInspector and TelemetryDispatchMessageInspector to be internal-only classes. The only documented/supported ways to use this library is via the TelemetryEndpointBehavior, TelemetryServiceBehavior, and/or TelemetryContractBehaviorAttribute so there is no need for the message inspectors to be public. Technically this is a breaking change, however consumers are likely never referencing these classes directly today as there is no need or reason for them to - they provide no additional capabilities over the published/documented way to consume this library.

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

• Appropriate CHANGELOG.md updated for non-trivial changes
• Design discussion issue #
• Changes in public API reviewed

[codecov]

Codecov Report

Merging #1376 (046f9ba) into main (71655ce) will increase coverage by 5.28%.
Report is 15 commits behind head on main.
The diff coverage is 81.35%.

@@            Coverage Diff             @@
##             main    #1376      +/-   ##
==========================================
+ Coverage   73.91%   79.20%   +5.28%     
==========================================
  Files         267       30     -237     
  Lines        9615      678    -8937     
==========================================
- Hits         7107      537    -6570     
+ Misses       2508      141    -2367     

Flag	Coverage Δ
unittests-Instrumentation.Wcf	79.20% <81.35%> (?)

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

Files	Coverage Δ
.../Implementation/TelemetryClientMessageInspector.cs	100.00% <ø> (ø)
...mplementation/TelemetryDispatchMessageInspector.cs	86.15% <ø> (ø)
...entation.Wcf/TelemetryContractBehaviorAttribute.cs	0.00% <ø> (ø)
...ry.Instrumentation.Wcf/TelemetryServiceBehavior.cs	0.00% <ø> (ø)
...rumentation.Wcf/TracerProviderBuilderExtensions.cs	88.88% <100.00%> (+1.38%)	⬆️
...cf/Implementation/WcfInstrumentationEventSource.cs	21.73% <0.00%> (-6.04%)	⬇️
...on.Wcf/Implementation/AspNetParentSpanCorrector.cs	88.67% <88.67%> (ø)

... and 237 files with indirect coverage changes

[CodeBlanch]

LGTM