Track server start

Summary:
Need to answer:

- How many starts a day over time

Reviewed By: antonk52

Differential Revision: D46219995

fbshipit-source-id: bffaeadf684a2d34c6e145784c5a86dbaf5f532a

desktop/flipper-server-core/src/utils/tracker.tsx

@@ -10,6 +10,7 @@
 import {getLogger} from 'flipper-common';
 
 type TrackerEvents = {
+  'server-started': {port: number; tcp: boolean};
   'server-auth-token-verification': {
     successful: boolean;
     present: boolean;