Added changes to AWSXRayPropagator

[AsakerMohd]

Changes

While doing some auto instrumentation testing, we found that adding the AWSXRayPropagator and AWS SDK instrumentation causes a conflict with the propagated X-Amzn-Trace-Id . This is a header that is used to propagate X-Ray trace context for trace linking. Lets assume we have an application that makes a call to AWS S3. There will be 2 activities in this case, the S3 activity created by the instrumentation Amazon.AWS.AWSClientInstrumentation and then a System.Net.Http.HttpRequestOut activity which is an http call to s3.amazonaws.com. The issue here is that when the httpRequest is created, the AWS SDK injects the traceHeader where the traceId and parent id is set to the Amazon.AWS.AWSClientInstrumentation S3 activity. However, since System.Net.Http.HttpRequestOut is the last outgoing call, the propagator injects the traceHeader from HttpRequestOut, basically overwriting the previous context.

To overcome this, a change is made is made so that If X-Amzn-Trace-Id already exists in the headers and the carrier is of HttpRequestMessage, This means that the request is coming from the AWS SDK Instrumentation library and in this case, we don't want to overwrite the propagation context from the AWS SDK Span with the context from the outgoing HttpRequestOut.

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

All modified and coverable lines are covered by tests ✅

Project coverage is 86.39%. Comparing base (71655ce) to head (c78563f).
Report is 642 commits behind head on main.

Additional details and impacted files

@@             Coverage Diff             @@
##             main    #2359       +/-   ##
===========================================
+ Coverage   73.91%   86.39%   +12.48%     
===========================================
  Files         267       34      -233     
  Lines        9615      897     -8718     
===========================================
- Hits         7107      775     -6332     
+ Misses       2508      122     -2386     

Flag	Coverage Δ
unittests-Instrumentation.AWS	86.39% <100.00%> (?)

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

Files with missing lines	Coverage Δ
...elemetry.Extensions.AWS/Trace/AWSXRayPropagator.cs	81.10% <100.00%> (+1.59%)	⬆️

... and 273 files with indirect coverage changes

[Kielek]

Please double check if it does not require changelog entry. Based on the answer, it can be merged as is.

[AsakerMohd]

Please double check if it does not require changelog entry. Based on the answer, it can be merged as is.

Yes it doesn't require any changelog entry so can be merged as is.

[Kielek]

Approving/merging based on @ppittle review.