Add support for ping command on windows in the simple node runner

Hi Dave,

This PR adds the support for the ping command in the simple node runner for Windows.
This way it is possible to do `mynode ping` on Linux and `mynode.cmd ping` on Windows.

If I spotted the issue correctly, the packaged `escript` cannot be executed on Windows and the consequence is that `nodetool` cannot be used right out of the box.
I fixed this issue either by:
-  copying `erl.ini` from my Erlang installation folder, this option is not viable since I relies on an installed Erlang on the system.
- or copying `start_clean.boot` in packaged erts bin directory, this is the option I implemented in this PR.

So what this PR actually does is to:
-  add the ping command to `simplenode.windows.runner.cmd`
- exclude all but 'start_clean.boot` in 'simplenode.reltool.config'
- use overlay to copy 'start_clean.boot` erts bin directory.

Tested with R16B only...

Cheers,
syl20bnr