util-lib: move a number of fs operations into fs-util.[ch]

src/timesync/timesyncd-manager.c

@@ -34,6 +34,7 @@
 #include "sd-daemon.h"
 
 #include "fd-util.h"
+#include "fs-util.h"
 #include "list.h"
 #include "log.h"
 #include "missing.h"

src/timesync/timesyncd.c

@@ -25,6 +25,7 @@
 #include "capability.h"
 #include "clock-util.h"
 #include "fd-util.h"
+#include "fs-util.h"
 #include "network-util.h"
 #include "signal-util.h"
 #include "timesyncd-conf.h"