[wsgi] make sure request.content is available for consumption
The wsgi.input stream is not seekable, so make a copy either to memory
or disk so it's still available to the user even after we've parsed it
(for POST form processing). Closes #3554996
[facet] create a RangeRQLPathFacet (closes #2852512)
This facet is a mix between a RQLPathFacet and a RangeFacet, allowing
to use the FacetRangeWidget on the RQLPathFacet target attribute