Add JSONP support to MappingJackson2JsonView

Enable JSONP support by wrapping the JSON output into
a callback when a JSONP query parameter specifying the
function name to use as callback is detected.

Default query parameter names recognized as JSONP ones
are "jsonp" and "callback". This list can be customized if
needed.

This commit also fixes JSONView support by removing
the view name specified in the model from the output.

Issue: SPR-8346
Polish MappingJackson2JsonView
Allow custom UrlPathHelper for WebSocket requests

Issue: SPR-117711