Convert time to a job decorator

CMakeLists.txt

@@ -117,7 +117,7 @@ SET(FISH_SRCS
     src/signal.cpp src/tinyexpr.cpp src/tnode.cpp src/tokenizer.cpp src/utf8.cpp src/util.cpp
     src/wcstringutil.cpp src/wgetopt.cpp src/wildcard.cpp src/wutil.cpp
     src/future_feature_flags.cpp src/redirection.cpp src/topic_monitor.cpp
-    src/flog.cpp src/trace.cpp src/builtin_time.cpp
+    src/flog.cpp src/trace.cpp src/timer.cpp
 )
 
 # Header files are just globbed.