Wait for async staging in stage_wrapper

Use stage_all and unstage_all to wait for staging
to complete when stage returns a Status rather than
blocking

bluesky/preprocessors.py

@@ -11,7 +11,8 @@
                     short_uid as _short_uid, make_decorator,
                     RunEngineControlException, merge_axis)
 from functools import wraps
-from .plan_stubs import (open_run, close_run, mv, pause, trigger_and_read, declare_stream)
+from .plan_stubs import (open_run, close_run, mv, pause, trigger_and_read,
+                         declare_stream, stage_all, unstage_all)
 
 
 def plan_mutator(plan, msg_proc):
@@ -950,12 +951,10 @@ def stage_wrapper(plan, devices):
     devices = separate_devices(root_ancestor(device) for device in devices)
 
     def stage_devices():
-        for d in devices:
-            yield Msg('stage', d)
+        yield from stage_all(*devices)
 
     def unstage_devices():
-        for d in reversed(devices):
-            yield Msg('unstage', d)
+        yield from unstage_all(*reversed(devices))
 
     def inner():
         yield from stage_devices()