test(adk): add WrapToolCall ToolMiddleware tests

[zhuangjie1125]

• Add 6 subtests for AgentMiddleware.WrapToolCall in TestChatModelAgentRun:
  • Invokable middleware: basic invocation, argument capture
  • Multiple middlewares: verify outer-to-inner execution order
  • Modify result: middleware can alter tool output
  • Streamable middleware: works with StreamableTool
  • EnhancedInvokable middleware: works with EnhancedInvokableTool
  • EnhancedStreamable middleware: works with EnhancedStreamableTool
• Add fakeEnhancedInvokableToolForTest and fakeEnhancedStreamableToolForTest helpers
• Fix collectToolMiddlewaresFromMiddlewares to also check EnhancedInvokable and EnhancedStreamable fields before skipping
• Fix deprecated comment in skill middleware (New -> NewMiddleware)

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 82.17%. Comparing base (867fc23) to head (ab60107).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #906      +/-   ##
==========================================
+ Coverage   81.98%   82.17%   +0.18%     
==========================================
  Files         146      146              
  Lines       16063    16063              
==========================================
+ Hits        13170    13200      +30     
+ Misses       1957     1916      -41     
- Partials      936      947      +11     

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