Watch and rebuild plugins

Summary: Now, once we build all plugins before we start Flipper, we need to rebuild some of them when they change. Previously, it was handled by Metro when we included plugins int he bundle, but we no longer include them in the bundle.

Reviewed By: lblasa

Differential Revision: D39510213

fbshipit-source-id: a352d78946f844a25d9127ac09c26e43e6739ca9

desktop/scripts/start-dev-server.tsx

@@ -362,9 +362,6 @@ async function startWatchChanges(io: socketIo.Server) {
         ),
       ),
     );
-    await startWatchPlugins(() => {
-      io.emit('refresh');
-    });
   } catch (err) {
     console.error(
       'Failed to start watching for changes using Watchman, continue without hot reloading',
@@ -448,6 +445,9 @@ function checkDevServer() {
   await startMetroServer(app, server);
   outputScreen(socket);
   await compileMain();
+  await startWatchPlugins(() => {
+    socket.emit('refresh');
+  });
   if (dotenv && dotenv.parsed) {
     console.log('✅  Loaded env vars from .env file: ', dotenv.parsed);
   }