chore: ActivityBridge Client Http External support

[tippmar-nr]

• Update ActivityBridge to handle Client activity kind for an external HTTP call
  • Creates the correct span name and attributes
  • Adds any OTel tags that weren't used when creating the ExternalSegmentData instance as User attributes on the segment
• Significant refactor in CompositeTests project to separate hybrid agent "smoke tests" from "general" tests
  • Added tests for external http activity to ensure code coverage
• Add support for http.statusText attribute on spanEvent (exists in the spanEvent spec but was marked "optional") and refactor as needed. Did not modify existing http client instrumentation to include that attribute.

[codecov-commenter]

Codecov Report

❌ Patch coverage is 87.80488% with 10 lines in your changes missing coverage. Please review.
✅ Project coverage is 82.36%. Comparing base (4399bc6) to head (c5ff178).
⚠️ Report is 254 commits behind head on main.

Files with missing lines	Patch %	Lines
...c/Agent/Core/OpenTelemetryBridge/ActivityBridge.cs	85.24%	7 Missing and 2 partials ⚠️
...Relic/Agent/Core/Utilities/DictionaryExtensions.cs	87.50%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #3151   +/-   ##
=======================================
  Coverage   82.35%   82.36%           
=======================================
  Files         479      479           
  Lines       31018    31094   +76     
  Branches     3526     3543   +17     
=======================================
+ Hits        25545    25610   +65     
- Misses       4653     4660    +7     
- Partials      820      824    +4     

Flag	Coverage Δ
Agent	83.41% <87.80%> (+<0.01%)	⬆️
Profiler	72.51% <ø> (ø)

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

Files with missing lines	Coverage Δ
...gent/Core/Attributes/AttributeDefinitionService.cs	95.76% <100.00%> (+0.05%)	⬆️
...ewRelic/Agent/Core/Segments/ExternalSegmentData.cs	98.38% <100.00%> (+0.05%)	⬆️
...nt/NewRelic/Agent/Core/Transactions/Transaction.cs	81.33% <100.00%> (ø)
...Relic/Agent/Core/Utilities/DictionaryExtensions.cs	20.00% <87.50%> (+9.47%)	⬆️
...c/Agent/Core/OpenTelemetryBridge/ActivityBridge.cs	84.58% <85.24%> (+0.20%)	⬆️

... and 1 file with indirect coverage changes

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