Add new service "file_tracker"

This new service periodically tracks the file open in the system.

Closes-Bug: #1995502
Change-Id: I02e097fef07655ff571af9f35bf258b2ed975098
diff --git a/lib/dstat b/lib/dstat
index eb03ae0..870c901 100644
--- a/lib/dstat
+++ b/lib/dstat
@@ -40,12 +40,18 @@
     if is_service_enabled peakmem_tracker; then
         die $LINENO "The peakmem_tracker service has been removed, use memory_tracker instead"
     fi
+
+    # To enable file_tracker add:
+    #    enable_service file_tracker
+    # to your localrc
+    run_process file_tracker "$TOP_DIR/tools/file_tracker.sh"
 }
 
 # stop_dstat() stop dstat process
 function stop_dstat {
     stop_process dstat
     stop_process memory_tracker
+    stop_process file_tracker
 }
 
 # Restore xtrace