Creates a url-encoded string describing the currently-selected item in search results.
UrlEncodeItem can be used to create HREFs to use in HTML search results. When the user clicks the link, the URL-encoded item will be sent as part of the Query String. A server-based application that receives the URL-encoded item can then use UrlDecodeItem to convert the data in the HREF back into a SearchResults object. This eliminates the need to keep the SearchResults object in memory between requests, making stateless operation possible on web servers.