Add requirements param to more Command APIs (#2059)

Assorted improvements to the ergonomics of declaring requirements in the new
command framework. C++ requirements list parameters have been defaulted
to an empty list, some missing C++ requirements list parameters have been
added, and both C++ and Java have been given requirements list params in
various InstantCommand wrapper methods (#2049), whose value is
forwarded to the command.

wpilibNewCommands/src/main/native/include/frc2/command/FunctionalCommand.h

@@ -35,7 +35,8 @@ class FunctionalCommand : public CommandHelper<CommandBase, FunctionalCommand> {
   FunctionalCommand(std::function<void()> onInit,
                     std::function<void()> onExecute,
                     std::function<void(bool)> onEnd,
-                    std::function<bool()> isFinished);
+                    std::function<bool()> isFinished,
+                    std::initializer_list<Subsystem*> requirements = {});
 
   FunctionalCommand(FunctionalCommand&& other) = default;