Add OpenAPI Call Constants in azure-ai-projects enums

[m7md7sien]

Description

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• The pull request does not introduce [breaking changes]
• CHANGELOG is updated for new features, bug fixes or other significant changes.
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Testing Guidelines

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[Copilot]

Pull request overview

This PR adds support for OpenAPI tool functionality by introducing two new enum constants to the ItemType enum: OPENAPI_CALL and OPENAPI_CALL_OUTPUT. These follow the established pattern of pairing call types with their corresponding output types, similar to existing entries like FUNCTION_CALL/FUNCTION_CALL_OUTPUT and MCP_CALL/MCP_APPROVAL_RESPONSE.

[Copilot]

The CHANGELOG mentions OpenAPI tool samples were added (lines 30-31) but does not document the addition of the new OPENAPI_CALL and OPENAPI_CALL_OUTPUT enum constants. Consider adding an entry under "Features Added" section to document these new ItemType enum values, such as: "Added OPENAPI_CALL and OPENAPI_CALL_OUTPUT to ItemType enum for OpenAPI tool support."

[github-actions]

API Change Check

APIView identified API level changes in this PR and created the following API reviews

azure-ai-projects