[wpilibc] Transition C++ classes to units::second_t (#3396)

A lot of these are breaking changes. frc::Timer was replaced with the
contents of frc2::Timer. The others were in-place argument changes or
removing deprecated non-unit overloads.

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

@@ -7,6 +7,7 @@
 #include <memory>
 
 #include <hal/Types.h>
+#include <units/time.h>
 
 #include "frc/AnalogTrigger.h"
 #include "frc/CounterBase.h"
@@ -368,7 +369,7 @@ class Counter : public CounterBase,
    *
    * @returns The period between the last two pulses in units of seconds.
    */
-  double GetPeriod() const override;
+  units::second_t GetPeriod() const override;
 
   /**
    * Set the maximum period where the device is still considered "moving".
@@ -380,7 +381,7 @@ class Counter : public CounterBase,
    * @param maxPeriod The maximum period where the counted device is considered
    *                  moving in seconds.
    */
-  void SetMaxPeriod(double maxPeriod) final;
+  void SetMaxPeriod(units::second_t maxPeriod) final;
 
   /**
    * Select whether you want to continue updating the event timer output when