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/control_loops/superstructure/superstructure.cc b/y2023/control_loops/superstructure/superstructure.cc
index 4919cd6..e11092a 100644
--- a/y2023/control_loops/superstructure/superstructure.cc
+++ b/y2023/control_loops/superstructure/superstructure.cc
@@ -10,9 +10,7 @@
 DEFINE_bool(ignore_distance, false,
             "If true, ignore distance when shooting and obay joystick_reader");
 
-namespace y2023 {
-namespace control_loops {
-namespace superstructure {
+namespace y2023::control_loops::superstructure {
 
 using ::aos::monotonic_clock;
 
@@ -148,6 +146,4 @@
                                               y2);
 }
 
-}  // namespace superstructure
-}  // namespace control_loops
-}  // namespace y2023
+}  // namespace y2023::control_loops::superstructure