feature request: add a way to debug ssh connection

[Paolo Benvenuto <paolobenve@gmail.com>]

I'm using git (2.25.1 on xubuntu 20.04), and I access to my remote via
ssh in order to authenticate with ssh key and not to have to use the
username/password pair.

Now, mi internet connection is very slow and unstable, and possibly
has other problems - I'm in Cuba.

Doing "git push" I often cannot connect to remote, sometimes it
connects, sometimes it doesn't.

"git push -v" adds verbosity only with reference to git

I think a "--ssh-verbose" options would be very useful and very simple
to implement. The only thing it must do is adding the -v option to the
ssh command (when it is used).

Also, if the user repeats it, it would add a repeated -v option to ssh command.

Thank you for your work on git!

don Paolo Benvenuto