[wpilib] Add functional interface equivalents to MotorController (#6053)

This does not deprecate any current functionality, but prepares the way for future deprecation.

The drive classes now accept void(double) functions, which makes them more flexible.

The C++ API ended up a bit more verbose, but the Java API is really concise with method references, which is >80% of our userbase. For example:

`DifferentialDrive drive = new DifferentialDrive(m_leftMotor::set, m_rightMotor::set);`

Lambdas can be passed to interoperate with vendor motor controller APIs that don't have e.g., set(double), so CTRE doesn't have to maintain their WPI_ classes anymore.

MotorControllerGroup was replaced with PWMMotorController.addFollower() for PWM motor controllers. Users of CAN motor controllers should use their vendor's follower functionality.

wpilibcIntegrationTests/src/main/native/cpp/MotorEncoderTest.cpp

@@ -6,6 +6,7 @@
 
 #include <gtest/gtest.h>
 #include <units/time.h>
+#include <wpi/deprecated.h>
 
 #include "TestBench.h"
 #include "frc/Encoder.h"
@@ -37,6 +38,8 @@ std::ostream& operator<<(std::ostream& os, MotorEncoderTestType const& type) {
 
 static constexpr auto kMotorTime = 0.5_s;
 
+WPI_IGNORE_DEPRECATED
+
 /**
  * A fixture that includes a PWM motor controller and an encoder connected to
  * the same motor.
@@ -197,3 +200,5 @@ TEST_P(MotorEncoderTest, Reset) {
 
 INSTANTIATE_TEST_SUITE_P(Tests, MotorEncoderTest,
                          testing::Values(TEST_VICTOR, TEST_JAGUAR, TEST_TALON));
+
+WPI_UNIGNORE_DEPRECATED