[network] Add empty protocol message handler

The empty handler ensures the backend protocol change is landable
without type errors.

Bug: chromium:1032063
Change-Id: Iaa12626e70c69db609a37b99d589c08d05689f2d
Reviewed-on: https://chromium-review.googlesource.com/c/devtools/devtools-frontend/+/1953781
Commit-Queue: Sigurd Schneider <sigurds@chromium.org>
Reviewed-by: Jan Scheffler <janscheffler@chromium.org>

front_end/sdk/NetworkManager.js

@@ -845,6 +845,17 @@ export class NetworkDispatcher {
     this._getExtraInfoBuilder(requestId).addResponseExtraInfo(extraResponseInfo);
   }
 
+  /**
+   * @unrestricted
+   * @param {boolean} isServiceWorker
+   * @param {string} url
+   * @param {string} firstPartyUrl
+   * @param {!Array<!Protocol.Network.BlockedCookieWithReason>} blockedCookies
+   */
+  cookiesBlocked(isServiceWorker, url, firstPartyUrl, blockedCookies) {
+    // TODO(chromium:1032063): Implement this protocol message handler.
+  }
+
   /**
    * @param {string} requestId
    * @return {!RedirectExtraInfoBuilder}