[dpkg] add `dpkg` spec

[mrhappyma]

Sanity checks

• [X] My issue relates to a specific CLI completion spec (e.g. git checkout is missing options in git completion spec). If your issue is more general, please create your issue here: withfig/fig
• [X] I have searched github.com/withfig/autocomplete/issues and there are no duplicates of my issue
• [X] I would like to work on this.

What CLI tool does this relate to?

dpkg

Which statement makes the most sense?

This completion spec does not exist

Issue Details

Resources: https://manpages.debian.org/stretch/dpkg/dpkg.1.en.html https://www.computerhope.com/unix/dpkg.htm

I might work on this later if I have time but maybe not, depends how stuff goes in the near future.