Register the `ballerina-platform/openapi-tools` code generator tool to repository

Hi Team,
We are currently developing an OpenAPI tool for the Ballerina language which is an open-source, cloud-native programming language specifically designed to simplify integration development for enterprise applications. Our tool has main 3 features

1. Generate Ballerina client stub for the given openAPI specification(v2, v3).
2. Generate Ballerina service skeleton for the given openAPI specification(v2, v3)
3. Generate OpenAPI specification(v3) for the given Ballerina service

Tool Properties

• Display name: Ballerina OpenAPI tool
• Description: The Ballerina OpenAPI tool enables the generation of Ballerina client and service skeleton from provided OpenAPI specifications (v2, v3) and facilitates the creation of OpenAPI v3 specifications for given Ballerina services.
• Repository: https://github.com/ballerina-platform/openapi-tools
• Homepage: https://ballerina.io/learn/openapi-tool/

OpenAPI Versions

• 3.1: true
• 3.0: true
• 2.0: true

Start by reading the repository's contribution guidance and inspecting how existing OpenAPI tools are represented; the issue names no file or test. Add the openapi-tools registration with the provided display name, description, repository, homepage, and supported versions, then verify it appears correctly in the repository's published tool collection.