[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".

datalogtool/src/main/native/cpp/Exporter.cpp

@@ -466,7 +466,8 @@ static void ValueToCsv(wpi::raw_ostream& os, const Entry& entry,
       fmt::print(os, "{}", val);
       return;
     }
-  } else if (entry.type == "int64") {
+  } else if (entry.type == "int64" || entry.type == "int") {
+    // support "int" for compatibility with old NT4 datalogs
     int64_t val;
     if (record.GetInteger(&val)) {
       fmt::print(os, "{}", val);