[Feature request]: Cache-bust endpoint URLs resource

[martincostello]

Is your feature request related to a specific problem? Or an existing feature?

Context: #3709 (comment)

The document URLs endpoint can get cached in browsers and go out-of-date.

Describe the solution you'd like

We should update the method below to respond with cache headers like we do for files:

Swashbuckle.AspNetCore/src/Swashbuckle.AspNetCore.SwaggerUI/SwaggerUIMiddleware.cs

Line 180 in c2cfe84

private async Task RespondWithDocumentUrls(HttpResponse response)

Swashbuckle.AspNetCore/src/Swashbuckle.AspNetCore.SwaggerUI/SwaggerUIMiddleware.cs

Line 158 in c2cfe84

SetHeaders(response, _options, etag);

Additional context

No response