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/y2022/control_loops/superstructure/catapult/catapult.cc b/y2022/control_loops/superstructure/catapult/catapult.cc
index b0ec6fd..493bb46 100644
--- a/y2022/control_loops/superstructure/catapult/catapult.cc
+++ b/y2022/control_loops/superstructure/catapult/catapult.cc
@@ -10,10 +10,7 @@
 #include "osqp.h"
 #include "y2022/control_loops/superstructure/catapult/catapult_plant.h"
 
-namespace y2022 {
-namespace control_loops {
-namespace superstructure {
-namespace catapult {
+namespace y2022::control_loops::superstructure::catapult {
 namespace chrono = std::chrono;
 
 namespace {
@@ -453,7 +450,4 @@
   return catapult_.MakeStatus(fbb);
 }
 
-}  // namespace catapult
-}  // namespace superstructure
-}  // namespace control_loops
-}  // namespace y2022
+}  // namespace y2022::control_loops::superstructure::catapult