Implement companion

Summary: Add Flipper Server Companion implementation. It extends the list of commands handled by Flipper Server by adding commands to interact with device or app Flipper plugins.

Reviewed By: mweststrate

Differential Revision: D36130159

fbshipit-source-id: 2eb6ba0fbae0fa850eadb7d417aa476240994bd5

desktop/flipper-server-companion/src/HeadlessClient.tsx

@@ -29,6 +29,11 @@ export class HeadlessClient extends AbstractClient {
     super(id, query, conn, logger, plugins, device, flipperServer);
   }
 
+  isBackgroundPlugin(_pluginId: string) {
+    // In headless context we treat every plugin as a non-background one because we do not want to start anything automatically to preseve resources
+    return false;
+  }
+
   // Headless client never starts plugins automaticaly to preserve server resources
   shouldConnectAsBackgroundPlugin() {
     return false;