[ntcore] Change Java event mask to EnumSet (#4564)

Also convert NetworkTableInstance.getNetworkMode() to return EnumSet.

wpilibj/src/main/java/edu/wpi/first/wpilibj/Preferences.java

@@ -17,6 +17,7 @@ import edu.wpi.first.networktables.NetworkTableListener;
 import edu.wpi.first.networktables.StringPublisher;
 import edu.wpi.first.networktables.Topic;
 import java.util.Collection;
+import java.util.EnumSet;
 
 /**
  * The preferences class provides a relatively simple way to save important values to the roboRIO to
@@ -77,7 +78,7 @@ public final class Preferences {
     m_listener =
         NetworkTableListener.createListener(
             m_tableSubscriber,
-            NetworkTableEvent.kImmediate | NetworkTableEvent.kPublish,
+            EnumSet.of(NetworkTableEvent.Kind.kImmediate, NetworkTableEvent.Kind.kPublish),
             event -> {
               if (event.topicInfo != null) {
                 Topic topic = event.topicInfo.getTopic();

wpilibj/src/main/java/edu/wpi/first/wpilibj/RobotBase.java

@@ -155,7 +155,7 @@ public abstract class RobotBase implements AutoCloseable {
     // wait for the NT server to actually start
     try {
       int count = 0;
-      while ((inst.getNetworkMode() & NetworkTableInstance.kNetModeStarting) != 0) {
+      while (inst.getNetworkMode().contains(NetworkTableInstance.NetworkMode.kStarting)) {
         Thread.sleep(10);
         count++;
         if (count > 100) {