(Server) Add a New Type to Capture Mocking

Summary:
per title

Note:
- This is a part of this PR: https://github.com/facebook/flipper/pull/488

Reviewed By: mweststrate

Differential Revision: D20440148

fbshipit-source-id: 9365f0b83449f295e819cccc2fa622d866dca129

desktop/plugins/network/types.tsx

@@ -25,6 +25,7 @@ export type Response = {
   reason: string;
   headers: Array<Header>;
   data: string | null | undefined;
+  isMock: boolean;
   insights: Insights | null | undefined;
 };
 
@@ -53,3 +54,10 @@ export type Insights = {
   transferSpeed: number | null | undefined;
   retries: RetryInsights | null | undefined;
 };
+
+export type Route = {
+  requestUrl: string;
+  requestMethod: string;
+  responseData: string;
+  responseHeaders: {[id: string]: Header};
+};