[ntcore] Use int64 for datalog type string (#5186)

There's a spec difference between NT4 and datalog for integers; NT4 uses
"int", datalog uses "int64". We were using "int" for datalog as well.

Also add backwards compatibility support to datalogtool for treating
"int" as "int64".

ntcore/src/main/native/cpp/LocalStorage.cpp

@@ -243,7 +243,7 @@ struct DataLoggerData {
   int Start(TopicData* topic, int64_t time) {
     return log.Start(fmt::format("{}{}", logPrefix,
                                  wpi::drop_front(topic->name, prefix.size())),
-                     topic->typeStr,
+                     topic->typeStr == "int" ? "int64" : topic->typeStr,
                      DataLoggerEntry::MakeMetadata(topic->propertiesStr), time);
   }