Remove statusbar and pimprogresswidget

The pimprogresswidgets was only used for the two keylist jobs
for X509 and OpenPGP "reload". This are quick local jobs
that also don't show progress (apart from done). They should also
not be cancellable as cancelling them leads to an invalid state
where kleopatra's internal keycache is not fully populated.

Progress for Jobs would make sense for the remote "Refresh" Jobs
but they currently don't have any progress signals.