Support HTTP range requests in Controllers

Prior to this commit, HTTP Range requests were only supported by the
ResourceHttpRequestHandler when serving static resources.

This commit improves the ResourceHttpMessageConverter that
now supports partial writes of Resources.
For this, the `HttpEntityMethodProcessor` and
`RequestResponseBodyMethodProcessor` now wrap resources with HTTP
range information in a `HttpRangeResource`, if necessary. The
message converter handle those types and knows how to handle partial
writes.

Controller methods can now handle Range requests for
return types that extend Resource or HttpEntity:

    @RequestMapping("/example/video.mp4")
    public Resource handler() { }

    @RequestMapping("/example/video.mp4")
    public HttpEntity<Resource> handler() { }

Issue: SPR-13834

spring-web/src/test/resources/org/springframework/http/converter/byterangeresource.txt

@@ -0,0 +1 @@
+Spring Framework test resource content.