[algoliasearch] add method addAlgoliaAgent (#37105)

source: https://github.com/algolia/algoliasearch-client-javascript/blob/5c1ce1308749aa0807940456393aa23ae46fb9eb/src/AlgoliaSearchCore.js#L173

types/algoliasearch/index.d.ts

@@ -211,6 +211,10 @@ declare namespace algoliasearch {
      * Get 1000 last events
      */
     getLogs(options: LogsOptions): Promise<{ logs: Log[] }>;
+    /**
+     * add a header, used for flagging InstantSearch implementations
+     */
+    addAlgoliaAgent(agent: string): void;
   }
   /**
    * Interface for the index algolia object

types/algoliasearch/lite/index.d.ts

@@ -76,6 +76,10 @@ declare namespace algoliasearch {
      * remove an extra header for all upcoming requests
      */
     unsetExtraHeader(name: string): void;
+    /**
+     * add a header, used for flagging InstantSearch implementations
+     */
+    addAlgoliaAgent(agent: string): void;
   }
 
   /**