This new `HttpMessageWriter` leverages the `ResourceRegionEncoder` to
write `ResourceRegion` to HTTP responses, thus supporting HTTP Range
requests.
Whenever possible, this message writer uses the zero copy support for
single range requests.
This `HttpMessageWriter` is never used directly, but is used as a
delegate by the `ResourceHttpMessageWriter`. When provided with the
`BOUNDARY_STRING_HINT`, the `ResourceRegionHttpMessageWriter`
adapts its behavior in order to write a single/multiple byte ranges.
Issue: SPR-14664
a7a9e36ca0