Display tensorboard widget as result of run_on_yarn

[jdlesage]

DoD

• Run_on_yarn spawns tensorboard iframe if running from a notebook

Implementation details
here the implementation of the widget in tensorflow2.0

def _display_ipython(port, height, display_handle):
  import IPython.display
  iframe = IPython.display.IFrame(
      src="http://localhost:%d" % port,
      height=height,
      width="100%",
  )
  if display_handle:
    display_handle.update(iframe)
  else:
IPython.display.display(iframe)

In case of tf-yarn, port and host of the tensorboard are stored in the skein kv-store