importd: add new bus calls for importing local tar and raw images

This also adds "machinectl import-raw" and "machinectl import-tar" to
wrap these new bus calls.

THe commands basically do for local files that "machinectl pull-raw" and
friends do for remote files.

src/import/pull.c

@@ -433,6 +433,8 @@ int main(int argc, char *argv[]) {
         if (r <= 0)
                 goto finish;
 
+        ignore_signals(SIGPIPE, -1);
+
         r = pull_main(argc, argv);
 
 finish: