Add A2A API round-trip support in extract/publish and all-types integration coverage

[Copilot]

This PR adds first-class handling for APIM Agent-to-Agent (A2A) APIs so apiops extract -> apiops publish can round-trip A2A artifacts without degrading A2A-specific behavior. It also extends the all-types integration scenario to include an A2A API with JSON-RPC and agent card settings.

• A2A behavior in extract/publish

  • extract now treats type: a2a as a no-spec API type (same class of behavior as websocket/mcp for spec export), avoiding OpenAPI export attempts for A2A endpoints.
  • publish now skips spec-import field injection for A2A APIs, preserving A2A API payload semantics instead of forcing OpenAPI import paths.

• Client export-format mapping

  • APIM client export format resolution now explicitly short-circuits for a2a, preventing unnecessary export calls for API types that do not use spec artifacts.

• Integration round-trip expansion (all-resource-types)

  • Added src-a2a-weather-agent to source-apim.bicep with:
    • type: 'a2a'
    • agent.id
    • a2aProperties (agent card path/backend URL)
    • jsonRpcProperties (runtime backend/path)
    • subscription key requirements
  • Updated expected extraction structure and protocol inventory docs to assert A2A artifacts and key fields.

• Unit coverage for A2A paths

  • Added focused tests to verify:
    • A2A skips spec export in extractor flow
    • A2A skips APIM spec fetch in client flow
    • A2A publish path does not inject spec import fields

properties: any({
  type: 'a2a'
  agent: { id: 'src-a2a-weather-agent' }
  a2aProperties: {
    agentCardPath: '/.well-known/agent.json'
    agentCardBackendUrl: 'https://src-a2a-weather-agent.example.com/.well-known/agent.json'
  }
  jsonRpcProperties: {
    backendUrl: 'https://src-a2a-weather-agent.example.com'
    path: '/'
  }
})