Spring stream interoperability

This project offers three integrations:

1. A WebClientHttpRequestFactory that redirects the RestTemplate API calls to a WebClient. Doing so, it is possible to use any connector that is written for the WebClient also with RestTemplateand to use a single configuration for the client that underlies this web client.
2. A JdkClientHttpRequestFactory for the JDK HTTP client to work with RestTemplate: while rest template is not (no longer) officially deprecated, its development has become dormant. If the RestTemplate should be used alongside Spring's WebClient, this connector allows to use the same underlying client for both APIs.
3. Decoders and body inserters/extractors for streams: The InputStreamDecoder allows to map the result of a request through the WebClient to an InputStream that makes bytes available as they arrive. For this, it must be registered as a codec in the web client's builder, and the stream must be closed to avoid leaking data. Without a codec, it offers similar integrations to read bodys as streams via streams using StreamBodyExtractors. And body's can be written to a request using StreamBodyInserters.