Nest all namespaces

The compiler supports this now.  We can type less going forward.
No functional changes.

Signed-off-by: Stephan Pleines <pleines.stephan@gmail.com>
Change-Id: I29d6fa4f9aacc0e381f1a7637294db0392466995
diff --git a/y2023/joystick_reader.cc b/y2023/joystick_reader.cc
index f4d9ea6..45418bc 100644
--- a/y2023/joystick_reader.cc
+++ b/y2023/joystick_reader.cc
@@ -39,9 +39,7 @@
 using y2023::control_loops::superstructure::RollerGoal;
 using Side = frc971::control_loops::drivetrain::RobotSide;
 
-namespace y2023 {
-namespace input {
-namespace joysticks {
+namespace y2023::input::joysticks {
 
 constexpr double kConeWrist = 0.4;
 constexpr double kCubeWrist = 1.0;
@@ -562,9 +560,7 @@
   const ArmSetpoint *current_setpoint_ = nullptr;
 };
 
-}  // namespace joysticks
-}  // namespace input
-}  // namespace y2023
+}  // namespace y2023::input::joysticks
 
 int main(int argc, char **argv) {
   ::aos::InitGoogle(&argc, &argv);