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/RunCommand.h

@@ -30,7 +30,7 @@ class RunCommand : public CommandHelper<CommandBase, RunCommand> {
    * @param requirements the subsystems to require
    */
   RunCommand(std::function<void()> toRun,
-             std::initializer_list<Subsystem*> requirements);
+             std::initializer_list<Subsystem*> requirements = {});
 
   RunCommand(RunCommand&& other) = default;