[command] Add withName inline decorator to Java (#2420)

This is an inline decorator for setting the name of a command
(equivalent to calling setName()).

It's not possible to implement this for C++, as it would slice the derived
class to return it by value.

wpilibNewCommands/src/main/java/edu/wpi/first/wpilibj2/command/CommandBase.java

@@ -1,5 +1,5 @@
 /*----------------------------------------------------------------------------*/
-/* Copyright (c) 2018-2019 FIRST. All Rights Reserved.                        */
+/* Copyright (c) 2018-2020 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.                                                               */
@@ -56,6 +56,18 @@ public abstract class CommandBase implements Sendable, Command {
     SendableRegistry.setName(this, name);
   }
 
+  /**
+  * Decorates this Command with a name.
+  * Is an inline function for #setName(String);
+  *
+  * @param name name
+  * @return the decorated Command
+  */
+  public Command withName(String name) {
+    this.setName(name);
+    return this;
+  }
+
   /**
    * Gets the subsystem name of this Command.
    *