Bug report, feature request or other request

**Describe the issue**
When using Microsoft.Azure.WebJobs.Extensions.OpenApi setting the content type: application/x-www-form-urlencoded on a OpenApiRequestBody attribute, SwaggerUI is not rendering the ui properly.

**To Reproduce**
Steps to reproduce the behavior:
1. Create an HTTP triggered function with OpenApi support
2. Add the OpenApiRequestBody attribute with content type se to: application/x-www-form-urlencoded
3. Run the function
4. navigate to /swagger/ui

**Expected behavior**
SwaggerUI should render a text box where the user can input the body when trying the function

**Screenshots**

**Environment (please complete the following information, if applicable):**
- OS: Windows
- Browser Chrome
- Version [e.g. 22]

**Additional context**
Add any other context about the problem here.

Start by reproducing the issue with an HTTP-triggered Azure Function using the OpenApiRequestBody attribute and content type application/x-www-form-urlencoded, then inspect the generated /swagger/ui behavior. Compare the rendered request body controls with the expected text box shown in the report; done means Swagger UI renders an editable body input for this content type.

Written by the indexing model from the issue text.