Migrating front protobuf encode/decode to ts-proto lib

The ts-proto lib has the huge advantage of producing code the "Typescript" way and not the "Java" way.
In particular, for "oneof" types in protobuf, it is generating "ADT" that can be used to check if we forgot or not to deal with a type.

front/src/Connexion/ConnectionManager.ts

@@ -280,7 +280,7 @@ class ConnectionManager {
                 reject(error);
             });
 
-            connection.onConnectingError((event: CloseEvent) => {
+            connection.connectionErrorStream.subscribe((event: CloseEvent) => {
                 console.log("An error occurred while connecting to socket server. Retrying");
                 reject(
                     new Error(
@@ -292,7 +292,7 @@ class ConnectionManager {
                 );
             });
 
-            connection.onConnect((connect: OnConnectInterface) => {
+            connection.roomJoinedMessageStream.subscribe((connect: OnConnectInterface) => {
                 resolve(connect);
             });
         }).catch((err) => {