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/aos/logging/dynamic_logging_test.cc b/aos/logging/dynamic_logging_test.cc
index 9b78113..70e491d 100644
--- a/aos/logging/dynamic_logging_test.cc
+++ b/aos/logging/dynamic_logging_test.cc
@@ -11,9 +11,7 @@
 
 using aos::testing::ArtifactPath;
 
-namespace aos {
-namespace logging {
-namespace testing {
+namespace aos::logging::testing {
 
 namespace chrono = std::chrono;
 
@@ -90,6 +88,4 @@
   }
 }
 
-}  // namespace testing
-}  // namespace logging
-}  // namespace aos
+}  // namespace aos::logging::testing