Split joystick_reader into hardware shim + application.

Change-Id: If31e6dd7ece547a2952ec21e2f4bc745ee6f9d84
diff --git a/frc971/input/joystick_proxy.cc b/frc971/input/joystick_proxy.cc
new file mode 100644
index 0000000..fe23f4a
--- /dev/null
+++ b/frc971/input/joystick_proxy.cc
@@ -0,0 +1,9 @@
+#include "aos/linux_code/init.h"
+#include "aos/prime/input/joystick_input.h"
+
+int main() {
+  ::aos::Init();
+  ::aos::input::JoystickProxy proxy;
+  proxy.Run();
+  ::aos::Cleanup();
+}