(PUP-2579) Improve regular expression for options of ssh_authorized_keys

An option of an SSH key containing escaped double quotes were not correctly
parsed by the ssh_authorized_keys provider, because of an incomplete
regular expression. This commit improves the regular expression by ensuring
that the option is ended by an non-escaped double quote.
Merge branch 'pr/2734'

* pr/2734:
  (PUP-2579) Improve regular expression for options of ssh_authorized_keys

Closes GH-2734