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.

wpilibcExamples/src/main/cpp/templates/commandv2skeleton/cpp/Robot.cpp

@@ -19,11 +19,11 @@ void Robot::DisabledPeriodic() {}
 void Robot::DisabledExit() {}
 
 void Robot::AutonomousInit() {
-  m_autonomousCommand = m_container.GetAutonomousCommand();
+  autonomousCommand = container.GetAutonomousCommand();
 
-  if (m_autonomousCommand) {
+  if (autonomousCommand) {
     wpi::cmd::CommandScheduler::GetInstance().Schedule(
-        m_autonomousCommand.value());
+        autonomousCommand.value());
   }
 }
 
@@ -32,8 +32,8 @@ void Robot::AutonomousPeriodic() {}
 void Robot::AutonomousExit() {}
 
 void Robot::TeleopInit() {
-  if (m_autonomousCommand) {
-    m_autonomousCommand->Cancel();
+  if (autonomousCommand) {
+    autonomousCommand->Cancel();
   }
 }
 

wpilibcExamples/src/main/cpp/templates/commandv2skeleton/include/Robot.hpp

@@ -28,7 +28,7 @@ class Robot : public wpi::TimedRobot {
   void UtilityExit() override;
 
  private:
-  std::optional<wpi::cmd::CommandPtr> m_autonomousCommand;
+  std::optional<wpi::cmd::CommandPtr> autonomousCommand;
 
-  RobotContainer m_container;
+  RobotContainer container;
 };