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/examples/HatchbotTraditional/include/subsystems/HatchSubsystem.hpp

@@ -30,5 +30,5 @@ class HatchSubsystem : public wpi::cmd::SubsystemBase {
  private:
   // Components (e.g. motor controllers and sensors) should generally be
   // declared private and exposed only through public methods.
-  wpi::DoubleSolenoid m_hatchSolenoid;
+  wpi::DoubleSolenoid hatchSolenoid;
 };