Using unstable netty api that has been removed broke jersey-container-netty-http

I do not have a solution at this time. Not that familiar with netty, and seems replacement class is not a drop in replacement. Jersey is using a unstable Netty api that was present in <=4.1.14, but removed in versions since >=4.1.15, in this [commit](https://github.com/netty/netty/commit/74f24a). Which breaks [HttpVersionChooser](https://github.com/jersey/jersey/blob/master/containers/netty-http/src/main/java/org/glassfish/jersey/netty/httpserver/HttpVersionChooser.java#L72) and [JerseyServerInitializer](https://github.com/jersey/jersey/blob/master/containers/netty-http/src/main/java/org/glassfish/jersey/netty/httpserver/JerseyServerInitializer.java#L140) usage of the removed class, Http2Codec.

I briefly looked into replacing Http2Codec with Http2MultipleCodec but was unsuccessful. I may see about a PR time permitting.Till then mentioning for others to be aware, and for the record.

Start with containers/netty-http/src/main/java/org/glassfish/jersey/netty/httpserver/HttpVersionChooser.java around line 72 and JerseyServerInitializer.java around line 140. Review Netty commit 74f24a and the Http2Codec removal, then compare the available replacement APIs. Done means jersey-container-netty-http works with Netty versions at or above 4.1.15.

Written by the indexing model from the issue text.