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/events/logging/config_remapper_test.cc b/aos/events/logging/config_remapper_test.cc
index a1fedb2..f33f421 100644
--- a/aos/events/logging/config_remapper_test.cc
+++ b/aos/events/logging/config_remapper_test.cc
@@ -14,8 +14,7 @@
 #include "aos/testing/tmpdir.h"
 #include "multinode_logger_test_lib.h"
 
-namespace aos {
-namespace testing {
+namespace aos::testing {
 using namespace logger::testing;
 using namespace logger;
 namespace chrono = std::chrono;
@@ -97,5 +96,4 @@
   EXPECT_EQ(channel->type()->string_view(), "aos.timing.Report");
 }
 
-}  // namespace testing
-}  // namespace aos
+}  // namespace aos::testing