[build] Add package declaration check to checkstyle (#2446)

Co-authored-by: Austin Shalit <austinshalit@gmail.com>

myRobot/src/main/java/frc/robot/MyRobot.java

@@ -0,0 +1,56 @@
+/*----------------------------------------------------------------------------*/
+/* Copyright (c) 2016-2020 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.                                                               */
+/*----------------------------------------------------------------------------*/
+
+package frc.robot;
+
+import edu.wpi.first.wpilibj.TimedRobot;
+
+@SuppressWarnings("all")
+public class MyRobot extends TimedRobot {
+  /**
+   * This function is run when the robot is first started up and should be
+   * used for any initialization code.
+   */
+  @Override
+  public void robotInit() {}
+
+  /**
+   * This function is run once each time the robot enters autonomous mode
+   */
+  @Override
+  public void autonomousInit() {}
+
+  /**
+   * This function is called periodically during autonomous
+   */
+  @Override
+  public void autonomousPeriodic() {}
+
+  /**
+   * This function is called once each time the robot enters tele-operated mode
+   */
+  @Override
+  public void teleopInit() {}
+
+  /**
+   * This function is called periodically during operator control
+   */
+  @Override
+  public void teleopPeriodic() {}
+
+  /**
+   * This function is called periodically during test mode
+   */
+  @Override
+  public void testPeriodic() {}
+
+  /**
+   * This function is called periodically during all modes
+   */
+  @Override
+  public void robotPeriodic() {}
+}