Extract functions from path recipe module so that step can depend on it

scripts/slave/recipe_modules/swarming/example.py

 # Copyright 2014 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 DEPS = [
+  'file',
   'isolate',
   'path',
   'properties',
   'python',
   'raw_io',
   'step',
   'swarming',
   'swarming_client',
 ]
 
@@ skipping 78 matching lines @@
   # Wait for all tasks to complete.
   for task in tasks:
     step_result = api.swarming.collect_task(task)
     state = step_result.json.output['shards'][0]['state']
     assert api.swarming.State.COMPLETED == state, state
     state_name = api.swarming.State.to_string(state)
     assert 'Completed' == state_name, state_name
     assert step_result.swarming_task in tasks
 
   # Cleanup.
-  api.path.rmtree('remove temp dir', temp_dir)
+  api.file.rmtree('remove temp dir', temp_dir)
 
 
 def GenTests(api):
   yield (
       api.test('basic_0.4') +
       api.step_data(
           'archive for win',
           stdout=api.raw_io.output('hash_for_win hello_world.isolated')) +
       api.step_data(
           'archive for linux',
@@ skipping 48 matching lines @@
           stdout=api.raw_io.output('hash_for_linux hello_world.isolated')) +
       api.step_data(
           'archive for mac',
           stdout=api.raw_io.output('hash_for_mac hello_world.isolated')) +
       api.properties(
           rietveld="https://codereview.chromium.org",
           issue="123",
           patchset="1001",
           simulated_version=(0, 5),
           show_isolated_out_in_collect_step=False))