[python] Add @responseAsBool Spector test cases and fix ConstantType response generation

[Copilot]

Adds Python mock API test coverage for the azure/client-generator-core/response-as-bool Spector scenario (TCGC @responseAsBool decorator), which was missing from the test suite.

Changes

• Dependency bump: @azure-tools/azure-http-specs → 0.1.0-alpha.40-dev.11 to pull in the response-as-bool spec

• Generator fix (builder_serializer.py): In DPG mode, when a response type is a ConstantType, the generator was emitting _deserialize(Literal[True], response.json()). HEAD responses have no body, so response.json() raises JSONDecodeError. The fix short-circuits to deserialized = True / deserialized = False directly:

  # Before (broken for HEAD with @responseAsBool)
  deserialized = _deserialize(Literal[True], response.json())
  
  # After
  deserialized = True

• New tests (test_azure_client_generator_core_response_as_bool.py + async counterpart): covers both scenarios defined by the spec:

  • exists() → HEAD 204 → True
  • not_exists() → HEAD 404 → False

Warning

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I tried to connect to the following addresses, but was blocked by firewall rules:

• dl.google.com
  • Triggering command: /usr/lib/apt/methods/https /usr/lib/apt/methods/https --ignore-workspace (dns block)
• https://api.github.com/repos/Azure/typespec-azure/pulls/4339/files
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• iojs.org
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If you need me to access, download, or install something from one of these locations, you can either:

• Configure Actions setup steps to set up my environment, which run before the firewall is enabled
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