Improve protobuf support (#2513)

Summary:
* Update protobuf library to support map types
* Improved usage messaging in UI
* Always attempt to decode requests with a protobuf definition
## Changelog
Improved protobuf support

Pull Request resolved: https://github.com/facebook/flipper/pull/2513

Reviewed By: mweststrate

Differential Revision: D30162379

Pulled By: passy

fbshipit-source-id: 201fb06045822641be5840b121da180a201be974

desktop/plugins/public/network/ProtobufDefinitionsRepository.tsx

@@ -63,6 +63,10 @@ export class ProtobufDefinitionsRepository {
     }
   }
 
+  public hasDefinition(method: string, path: string): boolean {
+    return this.rawDefinitions.hasOwnProperty(this.key(method, path));
+  }
+
   private generateRoots(key: string) {
     if (key in this.cachedDecodedDefinitions) {
       return;