Fixes#16 by replacing uses of the `apt_key:` module with `get_url:` to
download apt keyrings into `/etc/apt/keyrings`, then used
`signed-by=/etc/path/keyrings/<keyring>` in the appropriate sources.list
file.
Additionally:
* Stop using Chocolatey packages for 1password as they are not up to
date, instead download and install directly.
* Switch to apt repository on Debian.
* Add zsh completions for macOS and Dabian.
* Add powershell completions for Windows.
