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

android/plugins/retrofit2-protobuf/build.gradle

@@ -25,7 +25,7 @@ android {
         implementation project(':network-plugin')
         implementation deps.protobuf
         implementation "com.squareup.retrofit2:retrofit:2.9.0"
-        implementation "com.github.hbmartin:protobuf_java_to_protobufjs:0.1.0"
+        implementation "com.github.hbmartin:protobuf_java_to_protobufjs:0.2.0"
         compileOnly deps.jsr305
     }
 }