Instrumentation to store context object into Activity.CustomProperty

[cijothomas]

HttpClient, HttpWebRequest, Grpc, SqlClient, Asp.Net, Asp.NetCore instrumentations modified to

1. Store context object (context here refers to the HttpRequest, SqlComman) in activity as a customobject. (already existing in some cases)
2. The above is done only if AllDataRequested=true.
3. Tests to validate this.

TODOS:
Expose the key string for these objects publicly. This makes it easier to consumers to use it.
Write example which demonstrate the usage.

Unrelated to this PR: Refactor the Instrumentation Tests. Some have basic tests, more tests. It should be reorged.

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

• Design discussion issue #
• Changes in public API reviewed

[CodeBlanch]

In HttpWebRequestActivitySource.netfx.cs there is also Request & Response set, both before activity.IsAllDataRequested check. Did you leave them alone on purpose?

I don't think that's necessarily a bad thing. I intentionally put them all outside of the check for anyone wanting to do advanced things. Something like... make a sampling decision based on the raw requests. Or maybe have their own ActivityListeners? Not saying we must do that, I just thought it was worth the perf 🤷

[cijothomas]

I missed it. I prefer to keep everything inside AllDataRequested.

My general take is to follow what open telemetry spec suggests:
Samplers get a specific set of things - name, parentcontext, kind, initial attributes, links.
we don't want to provide more anything more, unless there is a strong reason to do it.

[cijothomas]

btw - samplers dont get access to raw Actiivty itself, so even if someone want to make intelligent sampling decision, they wont be able to leverage this custom obj.

[CodeBlanch]

Hah ok good point!

[CodeBlanch]

Let's also get Request & Response in HttpWebRequestActivitySource.netfx.cs. Otherwise looks good.

[codecov]

Codecov Report

Merging #1128 into master will increase coverage by 0.01%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master    #1128      +/-   ##
==========================================
+ Coverage   77.33%   77.34%   +0.01%     
==========================================
  Files         220      220              
  Lines        6256     6260       +4     
==========================================
+ Hits         4838     4842       +4     
  Misses       1418     1418              

Impacted Files	Coverage Δ
...umentation.AspNet/Implementation/HttpInListener.cs	92.85% <100.00%> (+0.17%)	⬆️
...tation.AspNetCore/Implementation/HttpInListener.cs	89.13% <100.00%> (+0.24%)	⬆️
...rpc/Implementation/GrpcClientDiagnosticListener.cs	89.65% <100.00%> (ø)
...tp/Implementation/HttpHandlerDiagnosticListener.cs	88.00% <100.00%> (ø)
...ient/Implementation/SqlClientDiagnosticListener.cs	78.46% <100.00%> (ø)
....Prometheus/PrometheusExporterMetricsHttpServer.cs	74.50% <0.00%> (-1.97%)	⬇️
...ter.ZPages/Implementation/ZPagesActivityTracker.cs	100.00% <0.00%> (+2.85%)	⬆️