tools: Suggest udisks2-lvm2 for Debian/Ubuntu
tools: Suggest udisks2-lvm2 for Debian/Ubuntu

We don't want to add a "strong" dependency like "Recommends:" or even
"Depends:": We don't want to pull LVM packages onto a system just
because the admin installs Cockpit.

But let's at least show it as a suggested add-on and explain why you may
want it.

Fixes #17041

martinpitt/cockpit,cockpit-project/cockpit,mvollmer/cockpit,cockpit-project/cockpit,mvollmer/cockpit,martinpitt/cockpit,martinpitt/cockpit,martinpitt/cockpit,cockpit-project/cockpit,cockpit-project/cockpit,mvollmer/cockpit,mvollmer/cockpit,cockpit-project/cockpit,mvollmer/cockpit,martinpitt/cockpit