Keep NZB search API supported/functional

Enabling all pro users to discover the same usenet links in the Stremio addon increases the likelihood of users finding cached content. Completely offloading this functionality to prowlarr/third party indexers is somewhat counterintuitive from this perspective since indexer usage would be dispersed. Prowlarr integration would be a welcomedf feature, but for the sake of finding cached content to improve the user experience, a common search is necessary.