[Feature Request] Support stoplightio/elements as new openapi ui

[miss85246]

Is your feature request related to a problem? Please describe your use case.
I’ve recently been using sanic-ext to generate my OpenAPI documentation.
I found that neither Swagger UI nor Redoc supports auto-generated code samples (such as curl, Python, etc.), which can be very useful in many cases.

While trying out Stoplight Elements, I discovered that it not only has a clean and modern UI, but also supports code samples, live request testing, and more.
I found it incredibly helpful and strongly recommend considering it for integration into sanic-ext.

Describe the solution you'd like
There is no need to change how openapi.json is generated.
Only a UI-level adaptation is needed to support Stoplight Elements as a new frontend interface option.

Additional context

1. A new element.html file can be added to the openapi/ui/ template directory, and the blueprint that serves the UI needs some minor modification to support this mode.
2. I have already replaced redoc.html locally and successfully verified that Stoplight Elements can be used as the UI for viewing the API documentation.