Add sshd pester tests (#789)

* add sshd tests

* add test for session child processes

* add sleep

* Update regress/pesterTests/SSHD.Tests.ps1

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

* update comments in test

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Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

Author: tgauth