ui: node/ACME: rework ACME grid for plugin based domains

ui: node/ACME: rework ACME grid for plugin based domains

This is basically a complete rework of the ACME grid.
Instead of having an ObjectGrid, we now have a normal
GridPanel which allows us to show a row for each Domain.

But to achieve this, we need to manually fill the store with data
from the 'acme' and 'acmedomainX' entries of the node config.

We also add an AccountSelector to the tbar and a link to the
datacenter->acme panel (when there is no account)

this also removes the 'register account' and 'view account' buttons,
since those are now available in datacenter->acme

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