Support HTTP2 traffic

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**Tell us about your request**
We are using App Runner mostly for frontend applications build with React/Next.js etc.

We are using custom build Nginx + Node.js Docker image (https://github.com/goforboom/mango) as proxy for Next.js applications. So we are able to route most of the heavy traffic (images, CSS files, static HTML, JavaScript) over Nginx proxy and cache it easily. But now we are stacked on HTTP 2 protocol. Because App Runner does not supports it. Requests from users browsers are very speed-sensitive. Right now as workaround we are using CloudFront as first layer between users and App Runner and its amazingly improves performance because HTTP2. Its possible to add support for HTTP2 protocol? It helps a lot!