add powershell (snap)

[airman604]

Add task to install Powershell as a snap package. Ansible snap module requires Ansible version 2.8, which is newer than the default apt package in Ubuntu 18.04, but can be installed with ppa: https://docs.ansible.com/ansible/latest/installation_guide/intro_installation.html#installing-ansible-on-ubuntu (only needs to be done on the Ansible host)