gui: GuestSummary: choose columns based on container width

gui: GuestSummary: choose columns based on container width

instead of the viewport width. This means that the number of columns can
change when the tree width changes, not only on browser window resize

for this to work reliably, we have to change the structure of the first
two panels, so that they are in one container for non-templates. if
we do not do this, there are some weird glitches on resizing with the
scrollbar

Signed-off-by: Dominik Csapak <d.csapak@proxmox.com>