autotest: Move _make_new_swarming_cmd to swarming_lib

This is where this function should go, next to the similar get_basic_swarming_cmd()

BUG=chromium:878956
TEST=None

Change-Id: Ifabbdd3226b8fe216cdfec9b1f5f423f22342ab1
Reviewed-on: https://chromium-review.googlesource.com/1208854
Commit-Ready: Allen Li <ayatane@chromium.org>
Tested-by: Allen Li <ayatane@chromium.org>
Reviewed-by: Prathmesh Prabhu <pprabhu@chromium.org>
diff --git a/venv/skylab_suite/swarming_lib.py b/venv/skylab_suite/swarming_lib.py
index e6a82eb..f3a271c 100644
--- a/venv/skylab_suite/swarming_lib.py
+++ b/venv/skylab_suite/swarming_lib.py
@@ -125,6 +125,11 @@
             '--swarming', os.environ.get('SWARMING_SERVER')]
 
 
+def get_new_task_swarming_cmd():
+    """Return a list of command args for creating a new task."""
+    return get_basic_swarming_cmd('post') + ['tasks/new']
+
+
 def make_fallback_request_dict(cmds, slices_dimensions, slices_expiration_secs,
                                task_name, priority, tags, user,
                                parent_task_id='',