Don't force public variables to use Hungarian notation (#8774)

People generally have expressed a dislike for the Hungarian notation
used in member variables, especially in examples/templates, and our
styleguide shouldn't be forced on downstream consumers, so this removes
all Hungarian notation from the examples/templates.

There are _some_ benefits to Hungarian for private member variables
(like knowing what's a member vs. local in a PR review) so we'll keep
private member variables the same for now, but public variables should
no longer use Hungarian notation, since it looks much worse. A new PMD
XPath rule has been added to accomplish this goal. Some other
non-compliant variables were fixed for the new rule.

cscore/src/main/java/org/wpilib/vision/camera/UsbCameraInfo.java

@@ -5,7 +5,6 @@
 package org.wpilib.vision.camera;
 
 /** USB camera information. */
-@SuppressWarnings("MemberName")
 public class UsbCameraInfo {
   /**
    * Create a new set of UsbCameraInfo.

cscore/src/main/java/org/wpilib/vision/camera/VideoEvent.java

@@ -5,7 +5,6 @@
 package org.wpilib.vision.camera;
 
 /** Video event. */
-@SuppressWarnings("MemberName")
 public class VideoEvent {
   /** VideoEvent kind. */
   public enum Kind {

cscore/src/main/java/org/wpilib/vision/camera/VideoMode.java

@@ -8,7 +8,6 @@ import java.util.Objects;
 import org.wpilib.util.PixelFormat;
 
 /** Video mode. */
-@SuppressWarnings("MemberName")
 public class VideoMode {
   /**
    * Create a new video mode.