Fix implicitly deleted move constructors (#1954)

These were incorrect and exhibited as warnings on more recent versions of
clang (notably on Mac).

- Use pointers instead of references internally in GenericHID and *Drive
- Leave PIDBase, PIDController, and Resource non-moveable
- Remove the atomic from m_disabled in NidecBrushless
- Make Timer and Trigger copyable as well as moveable
- Implement custom move constructor/assignment for SendableChooserBase

Also comment out some unused variables that caused clang warnings.

wpilibc/src/main/native/include/frc/Timer.h

@@ -57,6 +57,8 @@ class Timer {
 
   virtual ~Timer() = default;
 
+  Timer(const Timer& rhs);
+  Timer& operator=(const Timer& rhs);
   Timer(Timer&& rhs);
   Timer& operator=(Timer&& rhs);