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/vision/viewer_replay.cc b/y2022/vision/viewer_replay.cc
index 7e8c800..15427e4 100644
--- a/y2022/vision/viewer_replay.cc
+++ b/y2022/vision/viewer_replay.cc
@@ -26,8 +26,7 @@
 DEFINE_string(logger_pi_log, "/tmp/logger_pi/", "Path to logger pi log");
 DEFINE_string(roborio_log, "/tmp/roborio/", "Path to roborio log");
 
-namespace y2022 {
-namespace vision {
+namespace y2022::vision {
 namespace {
 
 using aos::monotonic_clock;
@@ -257,8 +256,7 @@
 }
 
 }  // namespace
-}  // namespace vision
-}  // namespace y2022
+}  // namespace y2022::vision
 
 // Quick and lightweight viewer for image logs
 int main(int argc, char **argv) {