feat: add support for require_approval argument when creating response (#3608)

# What does this PR do?
This PR adds support for the require_approval on an mcp tool definition
passed to create response in the Responses API. This allows the caller
to indicate whether they want to approve calls to that server, or let
them be called without approval.

Closes #3443

## Test Plan
Tested both approval and denial.
Added automated integration test for both cases.

---------

Signed-off-by: Gordon Sim <gsim@redhat.com>
Co-authored-by: Matthew Farrellee <matt@cs.wisc.edu>

docs/static/llama-stack-spec.yaml

@@ -6541,6 +6541,8 @@ components:
         - $ref: '#/components/schemas/OpenAIResponseOutputMessageFileSearchToolCall'
         - $ref: '#/components/schemas/OpenAIResponseOutputMessageFunctionToolCall'
         - $ref: '#/components/schemas/OpenAIResponseInputFunctionToolCallOutput'
+        - $ref: '#/components/schemas/OpenAIResponseMCPApprovalRequest'
+        - $ref: '#/components/schemas/OpenAIResponseMCPApprovalResponse'
         - $ref: '#/components/schemas/OpenAIResponseMessage'
     "OpenAIResponseInputFunctionToolCallOutput":
       type: object
@@ -6835,6 +6837,53 @@ components:
       title: OpenAIResponseInputToolWebSearch
       description: >-
         Web search tool configuration for OpenAI response inputs.
+    OpenAIResponseMCPApprovalRequest:
+      type: object
+      properties:
+        arguments:
+          type: string
+        id:
+          type: string
+        name:
+          type: string
+        server_label:
+          type: string
+        type:
+          type: string
+          const: mcp_approval_request
+          default: mcp_approval_request
+      additionalProperties: false
+      required:
+        - arguments
+        - id
+        - name
+        - server_label
+        - type
+      title: OpenAIResponseMCPApprovalRequest
+      description: >-
+        A request for human approval of a tool invocation.
+    OpenAIResponseMCPApprovalResponse:
+      type: object
+      properties:
+        approval_request_id:
+          type: string
+        approve:
+          type: boolean
+        type:
+          type: string
+          const: mcp_approval_response
+          default: mcp_approval_response
+        id:
+          type: string
+        reason:
+          type: string
+      additionalProperties: false
+      required:
+        - approval_request_id
+        - approve
+        - type
+      title: OpenAIResponseMCPApprovalResponse
+      description: A response to an MCP approval request.
     OpenAIResponseMessage:
       type: object
       properties:
@@ -7227,6 +7276,7 @@ components:
         - $ref: '#/components/schemas/OpenAIResponseOutputMessageFunctionToolCall'
         - $ref: '#/components/schemas/OpenAIResponseOutputMessageMCPCall'
         - $ref: '#/components/schemas/OpenAIResponseOutputMessageMCPListTools'
+        - $ref: '#/components/schemas/OpenAIResponseMCPApprovalRequest'
       discriminator:
         propertyName: type
         mapping:
@@ -7236,6 +7286,7 @@ components:
           function_call: '#/components/schemas/OpenAIResponseOutputMessageFunctionToolCall'
           mcp_call: '#/components/schemas/OpenAIResponseOutputMessageMCPCall'
           mcp_list_tools: '#/components/schemas/OpenAIResponseOutputMessageMCPListTools'
+          mcp_approval_request: '#/components/schemas/OpenAIResponseMCPApprovalRequest'
     OpenAIResponseOutputMessageMCPCall:
       type: object
       properties:
@@ -7785,6 +7836,7 @@ components:
             - $ref: '#/components/schemas/OpenAIResponseOutputMessageFunctionToolCall'
             - $ref: '#/components/schemas/OpenAIResponseOutputMessageMCPCall'
             - $ref: '#/components/schemas/OpenAIResponseOutputMessageMCPListTools'
+            - $ref: '#/components/schemas/OpenAIResponseMCPApprovalRequest'
           discriminator:
             propertyName: type
             mapping:
@@ -7794,6 +7846,7 @@ components:
               function_call: '#/components/schemas/OpenAIResponseOutputMessageFunctionToolCall'
               mcp_call: '#/components/schemas/OpenAIResponseOutputMessageMCPCall'
               mcp_list_tools: '#/components/schemas/OpenAIResponseOutputMessageMCPListTools'
+              mcp_approval_request: '#/components/schemas/OpenAIResponseMCPApprovalRequest'
           description: >-
             The output item that was added (message, tool call, etc.)
         output_index:
@@ -7836,6 +7889,7 @@ components:
             - $ref: '#/components/schemas/OpenAIResponseOutputMessageFunctionToolCall'
             - $ref: '#/components/schemas/OpenAIResponseOutputMessageMCPCall'
             - $ref: '#/components/schemas/OpenAIResponseOutputMessageMCPListTools'
+            - $ref: '#/components/schemas/OpenAIResponseMCPApprovalRequest'
           discriminator:
             propertyName: type
             mapping:
@@ -7845,6 +7899,7 @@ components:
               function_call: '#/components/schemas/OpenAIResponseOutputMessageFunctionToolCall'
               mcp_call: '#/components/schemas/OpenAIResponseOutputMessageMCPCall'
               mcp_list_tools: '#/components/schemas/OpenAIResponseOutputMessageMCPListTools'
+              mcp_approval_request: '#/components/schemas/OpenAIResponseMCPApprovalRequest'
           description: >-
             The completed output item (message, tool call, etc.)
         output_index: