added port argument for ssh (#4117)
* added port argument for ssh
* changed arg name; moved PDSH arg; added if-else for arg
* fixed missing key error
* updated test code to correspond to the change in multinode_re_runner.py
* changed default ssh port to None
* Update deepspeed/launcher/runner.py
* formatting
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Co-authored-by: Logan Adams <114770087+loadams@users.noreply.github.com>
Co-authored-by: Michael Wyatt <mrwyattii@gmail.com>
