Add OpenAPI endpoint to Company.WebApplication1.http

[mikekistler]

Add OpenAPI endpoint to Company.WebApplication1.http

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This PR adds a request to the OpenAPI endpoint in the http file for C# webapi projects.

[Copilot]

Pull request overview

This PR adds an HTTP request for the OpenAPI endpoint (/openapi/v1.json) to the .http file used in the C# Web API project template, making it easier for developers to test the OpenAPI documentation endpoint alongside the weather forecast API.

Key changes:

• Added a GET request to /openapi/v1.json with JSON accept header
• Positioned before the existing weather forecast endpoint request