[HttpClient] Add error.type for traces and metrics

[vishweshbankwar]

Fixes #
Design discussion issue #

Changes

Adds error.type attribute to activity and http.client.request.duration for HttpClient for non-netframework targets.

1. Adds error.type attribute to activity for netstandard, net6.0 , net7.0 and net8.0 targets. For net8.0 target the value will vary due to the addition of HttpRequestError Enum, which allows further drilldown of HttpRequestException \ HttpIOExceptiontype. This is in sync with how the tag is emitted on httpclient.request.duration metric on .NET8.0.
2. Adds error.type attribute to http.client.request.duration metric for netstandard, net6.0 and net7.0 targets. On net8.0, metric will be emitted via added meter System.Net.Http within instrumentation library.

TODO: Cover HttpWebRequest.

Merge requirement checklist

• CONTRIBUTING guidelines followed (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

Merging #5005 (783ef33) into main (f2ab976) will decrease coverage by 0.31%.
Report is 1 commits behind head on main.
The diff coverage is 78.75%.

@@            Coverage Diff             @@
##             main    #5005      +/-   ##
==========================================
- Coverage   83.69%   83.39%   -0.31%     
==========================================
  Files         296      296              
  Lines       12403    12452      +49     
==========================================
+ Hits        10381    10384       +3     
- Misses       2022     2068      +46     

Flag	Coverage Δ
unittests	83.39% <78.75%> (-0.31%)	⬇️

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

Files	Coverage Δ
...ementation/HttpHandlerMetricsDiagnosticListener.cs	90.14% <87.27%> (-7.64%)	⬇️
...tp/Implementation/HttpHandlerDiagnosticListener.cs	73.50% <60.00%> (-3.06%)	⬇️

... and 7 files with indirect coverage changes

[cijothomas]

is this change related to "error.type" ?

[vishweshbankwar]

No, this was there already

opentelemetry-dotnet/src/OpenTelemetry.Instrumentation.Http/Implementation/HttpHandlerDiagnosticListener.cs

Lines 284 to 287 in 5345863

	if (currentStatusCode == ActivityStatusCode.Unset)
	{
	activity.SetStatus(SpanHelper.ResolveSpanStatusForHttpStatusCode(activity.Kind, (int)response.StatusCode));
	}

. I just moved it to the top.

[utpilla]

LGTM. Tests should be simplified once #4928 is addressed.

[CodeBlanch]

LGTM