Cancel pending search request if a new search is made

[Enet4]

On the search page, it is possible to issue another search while the app is waiting for the full list of results. However, that other request isn't cancelled, and will still override the search results once they are resolved. This may be unwanted in cases where the user input a long-running query and then replaced it with a faster one.

When submitting a search through the web applications, any pending request should be cancelled.