Extend parsing ssh prompt

Summary:
* Add support for yes/no questions from ssh-agent and openssh client
* Add support for more openssh client prompt lines
* Better support for parsing git credential strings

I wrote this patch 5 years ago and sent it to Armin Berres, current
maintainer in that year. Seems it was never applied. Now I ported it for
the last ksshaskpass version.

Reviewers: fvogt

Reviewed By: fvogt

Subscribers: lbeltrame, ngraham, fvogt, plasma-devel

Tags: #plasma

Differential Revision: https://phabricator.kde.org/D9875