Update last of existing services to use repositories, includes unit tests

Also update PHPDocs on all the repository interfaces and classes to be correct.

app/Contracts/Repository/Attributes/SearchableInterface.php

@@ -26,5 +26,11 @@ namespace Pterodactyl\Contracts\Repository\Attributes;
 
 interface SearchableInterface
 {
+    /**
+     * Filter results by search term.
+     *
+     * @param  string $term
+     * @return $this
+     */
     public function search($term);
 }