[examples] Add tasks to run Java examples (#2920)

Example: ./gradlew :wpilibjExamples:runstatespacedifferentialdrivesimulation

wpilibjExamples/src/dev/native/cpp/main.cpp

@@ -0,0 +1,8 @@
+/*----------------------------------------------------------------------------*/
+/* Copyright (c) 2020 FIRST. All Rights Reserved.                             */
+/* Open Source Software - may be modified and shared by FRC teams. The code   */
+/* must be accompanied by the FIRST BSD license file in the root directory of */
+/* the project.                                                               */
+/*----------------------------------------------------------------------------*/
+
+int main() {}