Add subcomponent attribute support for Strands and Autogen agent/tool spans

[sgoel-nr]

Summary

• Adds a subcomponent span attribute to agent and tool FunctionTrace spans in both Strands and Autogen instrumentation hooks
• The attribute is a JSON-encoded string containing type (APM-AI_AGENT or APM-AI_TOOL) and name (the agent or tool name), enabling downstream systems to identify and classify agentic subcomponents within a trace
• Registers subcomponent as an allowed agent attribute in the core attribute allowlist
• Adds validate_span_events assertions to existing Autogen tests (assistant agent and teams) to verify the attribute is present with correct values

[github-actions]

✅MegaLinter analysis: Success

Descriptor	Linter	Files	Fixed	Errors	Warnings	Elapsed time
✅ ACTION	actionlint	7		0	0	1.01s
✅ MARKDOWN	markdownlint	7	0	0	0	1.43s
✅ PYTHON	ruff	967	0	0	0	1.06s
✅ PYTHON	ruff-format	967	0	0	0	0.37s
✅ YAML	prettier	15	0	0	0	1.49s
✅ YAML	v8r	15		0	0	4.85s
✅ YAML	yamllint	15		0	0	0.68s

See detailed reports in MegaLinter artifacts

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 81.71%. Comparing base (1efa4a5) to head (ab9733c).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1651      +/-   ##
==========================================
- Coverage   81.71%   81.71%   -0.01%     
==========================================
  Files         210      210              
  Lines       24690    24697       +7     
  Branches     3884     3884              
==========================================
+ Hits        20175    20180       +5     
- Misses       3198     3200       +2     
  Partials     1317     1317              

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[TimPansino]

Superseded by #1666